Fix incorrect usage of `lstrip()` and `rstrip()`

* what we actually want to do is `removeprefix()` and `removesuffix()`

invenio_config_tuw/notifications/backends.py

@@ -29,7 +29,7 @@ def temp_hack_notification_type(notification):
         notification, "template_name", notification.context.get("template_name", None)
     )
     if temp_type:
-        notification.type = temp_type.rstrip(".jinja")
+        notification.type = temp_type.removesuffix(".jinja")
 
     yield notification
     notification.type = old_notif_type

invenio_config_tuw/startup/config.py

@@ -81,7 +81,7 @@ def _make_site_url(suffix):
         url = current_app.config.get("THEME_SITEURL", "")
 
     # do a little dance to make sure there's no extra slashes
-    return (url.rstrip("/") + "/" + suffix.lstrip("/")).rstrip("/")
+    return (url.removesuffix("/") + "/" + suffix.removeprefix("/")).removesuffix("/")
 
 
 def assemble_db_uri_from_parts(app):
@@ -186,7 +186,9 @@ def assemble_site_urls_from_parts(app):
         theme_siteurl = theme_siteurl or f"{preferred_scheme}://{server_name}"
 
     elif theme_siteurl:
-        server_name = theme_siteurl.lstrip("http://").lstrip("https://").split("/")[0]
+        server_name = (
+            theme_siteurl.removeprefix("http://").removeprefix("https://").split("/")[0]
+        )
         app.logger.info(
             f"No SERVER_NAME set, calculated value '{server_name}' from THEME_SITEURL: '{theme_siteurl}'"
         )