switch destination directory for apt signing keys (#28639)

According to [Debian
docs](https://wiki.debian.org/DebianRepository/UseThirdParty):

> The certificate MUST NOT be placed in /etc/apt/trusted.gpg.d or loaded
by apt-key add.
> ...
> If future updates to the certificate will be managed by an apt/dpkg
package as recommended below, then it SHOULD be downloaded into
/usr/share/keyrings using the same filename that will be provided by the
package. If it will be managed locally , it SHOULD be downloaded into
/etc/apt/keyrings instead.
> ...
> A sources.list entry SHOULD have the signed-by option set.

docs/content/usage/packages/debian.en-us.md

@@ -27,7 +27,7 @@ The following examples use `apt`.
 To register the Debian registry add the url to the list of known apt sources:
 
 ```shell
-echo "deb https://gitea.example.com/api/packages/{owner}/debian {distribution} {component}" | sudo tee -a /etc/apt/sources.list.d/gitea.list
+echo "deb [signed-by=/etc/apt/keyrings/gitea-{owner}.asc] https://gitea.example.com/api/packages/{owner}/debian {distribution} {component}" | sudo tee -a /etc/apt/sources.list.d/gitea.list
 ```
 
 | Placeholder    | Description |
@@ -39,13 +39,13 @@ echo "deb https://gitea.example.com/api/packages/{owner}/debian {distribution} {
 If the registry is private, provide credentials in the url. You can use a password or a [personal access token](development/api-usage.md#authentication):
 
 ```shell
-echo "deb https://{username}:{your_password_or_token}@gitea.example.com/api/packages/{owner}/debian {distribution} {component}" | sudo tee -a /etc/apt/sources.list.d/gitea.list
+echo "deb [signed-by=/etc/apt/keyrings/gitea-{owner}.asc] https://{username}:{your_password_or_token}@gitea.example.com/api/packages/{owner}/debian {distribution} {component}" | sudo tee -a /etc/apt/sources.list.d/gitea.list
 ```
 
 The Debian registry files are signed with a PGP key which must be known to apt:
 
 ```shell
-sudo curl https://gitea.example.com/api/packages/{owner}/debian/repository.key -o /etc/apt/trusted.gpg.d/gitea-{owner}.asc
+sudo curl https://gitea.example.com/api/packages/{owner}/debian/repository.key -o /etc/apt/keyrings/gitea-{owner}.asc
 ```
 
 Afterwards update the local package index:

docs/content/usage/packages/debian.zh-cn.md

@@ -27,7 +27,7 @@ menu:
 要注册 Debian 注册表，请将 URL 添加到已知 `apt` 源列表中：
 
 ```shell
-echo "deb https://gitea.example.com/api/packages/{owner}/debian {distribution} {component}" | sudo tee -a /etc/apt/sources.list.d/gitea.list
+echo "deb [signed-by=/etc/apt/keyrings/gitea-{owner}.asc] https://gitea.example.com/api/packages/{owner}/debian {distribution} {component}" | sudo tee -a /etc/apt/sources.list.d/gitea.list
 ```
 
 | 占位符         | 描述           |
@@ -39,13 +39,13 @@ echo "deb https://gitea.example.com/api/packages/{owner}/debian {distribution} {
 如果注册表是私有的，请在 URL 中提供凭据。您可以使用密码或[个人访问令牌](development/api-usage.md#通过-api-认证)：
 
 ```shell
-echo "deb https://{username}:{your_password_or_token}@gitea.example.com/api/packages/{owner}/debian {distribution} {component}" | sudo tee -a /etc/apt/sources.list.d/gitea.list
+echo "deb [signed-by=/etc/apt/keyrings/gitea-{owner}.asc] https://{username}:{your_password_or_token}@gitea.example.com/api/packages/{owner}/debian {distribution} {component}" | sudo tee -a /etc/apt/sources.list.d/gitea.list
 ```
 
 Debian 注册表文件使用 PGP 密钥进行签名，`apt` 必须知道该密钥：
 
 ```shell
-sudo curl https://gitea.example.com/api/packages/{owner}/debian/repository.key -o /etc/apt/trusted.gpg.d/gitea-{owner}.asc
+sudo curl https://gitea.example.com/api/packages/{owner}/debian/repository.key -o /etc/apt/keyrings/gitea-{owner}.asc
 ```
 
 然后更新本地软件包索引：

templates/package/content/debian.tmpl

@@ -4,8 +4,8 @@
 		<div class="ui form">
 			<div class="field">
 				<label>{{svg "octicon-terminal"}} {{ctx.Locale.Tr "packages.debian.registry"}}</label>
-				<div class="markup"><pre class="code-block"><code>sudo curl <gitea-origin-url data-url="{{AppSubUrl}}/api/packages/{{$.PackageDescriptor.Owner.Name}}/debian/repository.key"></gitea-origin-url> -o /etc/apt/trusted.gpg.d/gitea-{{$.PackageDescriptor.Owner.Name}}.asc
-echo "deb <gitea-origin-url data-url="{{AppSubUrl}}/api/packages/{{$.PackageDescriptor.Owner.Name}}/debian"></gitea-origin-url> $distribution $component" | sudo tee -a /etc/apt/sources.list.d/gitea.list
+				<div class="markup"><pre class="code-block"><code>sudo curl <gitea-origin-url data-url="{{AppSubUrl}}/api/packages/{{$.PackageDescriptor.Owner.Name}}/debian/repository.key"></gitea-origin-url> -o /etc/apt/keyrings/gitea-{{$.PackageDescriptor.Owner.Name}}.asc
+echo "deb [signed-by=/etc/apt/keyrings/gitea-{{$.PackageDescriptor.Owner.Name}}.asc] <gitea-origin-url data-url="{{AppSubUrl}}/api/packages/{{$.PackageDescriptor.Owner.Name}}/debian"></gitea-origin-url> $distribution $component" | sudo tee -a /etc/apt/sources.list.d/gitea.list
 sudo apt update</code></pre></div>
 				<p>{{ctx.Locale.Tr "packages.debian.registry.info" | Safe}}</p>
 			</div>