Fix unable to display individual-level project (#26198)

As title

Before:

![image](https://github.com/go-gitea/gitea/assets/50507092/94afc3bf-5597-4151-a59b-5632840ffa21)

After:

![image](https://github.com/go-gitea/gitea/assets/50507092/df81aa0b-98a6-477d-a270-2e45b3dca0fc)

fix #26189

routers/web/repo/issue.go

@@ -518,6 +518,12 @@ func RetrieveRepoMilestonesAndAssignees(ctx *context.Context, repo *repo_model.R
 }
 
 func retrieveProjects(ctx *context.Context, repo *repo_model.Repository) {
+	// Distinguish whether the owner of the repository
+	// is an individual or an organization
+	repoOwnerType := project_model.TypeIndividual
+	if repo.Owner.IsOrganization() {
+		repoOwnerType = project_model.TypeOrganization
+	}
 	var err error
 	projects, _, err := project_model.FindProjects(ctx, project_model.SearchOptions{
 		RepoID:   repo.ID,
@@ -533,7 +539,7 @@ func retrieveProjects(ctx *context.Context, repo *repo_model.Repository) {
 		OwnerID:  repo.OwnerID,
 		Page:     -1,
 		IsClosed: util.OptionalBoolFalse,
-		Type:     project_model.TypeOrganization,
+		Type:     repoOwnerType,
 	})
 	if err != nil {
 		ctx.ServerError("GetProjects", err)
@@ -556,7 +562,7 @@ func retrieveProjects(ctx *context.Context, repo *repo_model.Repository) {
 		OwnerID:  repo.OwnerID,
 		Page:     -1,
 		IsClosed: util.OptionalBoolTrue,
-		Type:     project_model.TypeOrganization,
+		Type:     repoOwnerType,
 	})
 	if err != nil {
 		ctx.ServerError("GetProjects", err)