Feature: GitLab url from ENV (#14221)

<!-- Thank you for contributing to LangChain!

Replace this entire comment with:
  - **Description:** add gitlab url from env, 
  - **Issue:** no issue,
  - **Dependencies:** no,
- **Tag maintainer:** for a quicker response, tag the relevant
maintainer (see below),
- **Twitter handle:** we announce bigger features on Twitter. If your PR
gets announced, and you'd like a mention, we'll gladly shout you out!

Please make sure your PR is passing linting and testing before
submitting. Run `make format`, `make lint` and `make test` to check this
locally.

See contribution guidelines for more information on how to write/run
tests, lint, etc:

https://github.com/langchain-ai/langchain/blob/master/.github/CONTRIBUTING.md

If you're adding a new integration, please include:
1. a test for the integration, preferably unit tests that do not rely on
network access,
2. an example notebook showing its use. It lives in `docs/extras`
directory.

If no one reviews your PR within a few days, please @-mention one of
@baskaryan, @eyurtsev, @hwchase17.
 -->

---------

Co-authored-by: Erick Friis <erick@langchain.dev>

docs/docs/integrations/toolkits/gitlab.ipynb

@@ -77,6 +77,7 @@
     "\n",
     "Before initializing your agent, the following environmental variables need to be set:\n",
     "\n",
+    "* **GITLAB_URL** - The URL hosted Gitlab. Defaults to \"https://gitlab.com\". \n",
     "* **GITLAB_PERSONAL_ACCESS_TOKEN**- The personal access token you created in the last step\n",
     "* **GITLAB_REPOSITORY**- The name of the Gitlab repository you want your bot to act upon. Must follow the format {username}/{repo-name}.\n",
     "* **GITLAB_BRANCH**- The branch where the bot will make its commits. Defaults to 'main.'\n",
@@ -111,6 +112,7 @@
    "outputs": [],
    "source": [
     "# Set your environment variables using os.environ\n",
+    "os.environ[\"GITLAB_URL\"] = \"https://gitlab.example.org\"\n",
     "os.environ[\"GITLAB_PERSONAL_ACCESS_TOKEN\"] = \"\"\n",
     "os.environ[\"GITLAB_REPOSITORY\"] = \"username/repo-name\"\n",
     "os.environ[\"GITLAB_BRANCH\"] = \"bot-branch-name\"\n",

libs/langchain/langchain/utilities/gitlab.py

@@ -38,6 +38,10 @@ class GitLabAPIWrapper(BaseModel):
     @root_validator()
     def validate_environment(cls, values: Dict) -> Dict:
         """Validate that api key and python package exists in environment."""
+
+        gitlab_url = get_from_dict_or_env(
+            values, "gitlab_url", "GITLAB_URL", default=None
+        )
         gitlab_repository = get_from_dict_or_env(
             values, "gitlab_repository", "GITLAB_REPOSITORY"
         )
@@ -62,7 +66,11 @@ class GitLabAPIWrapper(BaseModel):
                 "Please install it with `pip install python-gitlab`"
             )
 
-        g = gitlab.Gitlab(private_token=gitlab_personal_access_token)
+        g = gitlab.Gitlab(
+            url=gitlab_url,
+            private_token=gitlab_personal_access_token,
+            keep_base_url=True,
+        )
 
         g.auth()