Replace gitlab.com with gitlab.postmarketos.org

Try to finish the migration by changing various links and texts to point to the new GitLab instance.

pmb/__init__.py

@@ -141,7 +141,9 @@ def main() -> int:
         print_log_hint()
         print()
         print("Before you report this error, ensure that pmbootstrap is " "up to date.")
-        print("Find the latest version here:" " https://gitlab.postmarketos.org/postmarketOS/pmbootstrap/-/tags")
+        print(
+            "Find the latest version here: https://gitlab.postmarketos.org/postmarketOS/pmbootstrap/-/tags"
+        )
         print(f"Your version: {__version__}")
         return 1