[BUG] Initalize Git for hook regeneration

- The hook regeneration code relies on `git.SupportProcReceive` being
set to determine if the `proc-receive` hook should be written, this
variable is set when the git module is initialized.
- Resolves #2414

cmd/admin_regenerate.go

@@ -5,6 +5,7 @@ package cmd
 
 import (
 	asymkey_model "code.gitea.io/gitea/models/asymkey"
+	"code.gitea.io/gitea/modules/git"
 	"code.gitea.io/gitea/modules/graceful"
 	repo_service "code.gitea.io/gitea/services/repository"
 
@@ -32,6 +33,12 @@ func runRegenerateHooks(_ *cli.Context) error {
 	if err := initDB(ctx); err != nil {
 		return err
 	}
+
+	// Detection of ProcReceive support relies on Git module being initalized.
+	if err := git.InitFull(ctx); err != nil {
+		return err
+	}
+
 	return repo_service.SyncRepositoryHooks(graceful.GetManager().ShutdownContext())
 }