Adopt ruff in CI (#5)

* Dropping pylint, isort and flake8 in favor of ruff

## By Submitting this PR I confirm:
- I am familiar with the [Contributing Guidelines](https://github.com/NVIDIA/NeMo-Agent-Toolkit/blob/develop/docs/source/resources/contributing.md).
- We require that all contributors "sign-off" on their commits. This certifies that the contribution is your original work, or you have rights to submit it under the same license, or a compatible license.
  - Any contribution which contains commits that are not Signed-Off will not be accepted.
- When the PR is ready for review, new or existing tests cover these changes.
- When the PR is ready for review, the documentation is up to date with these changes.




## Summary by CodeRabbit

- Chores
  - Migrated linting to Ruff and updated pre-commit hooks for a streamlined developer workflow.
  - Removed legacy lint/format tools and configurations to reduce maintenance overhead.
- Style
  - Standardized code style and import ordering via Ruff, with a 120-character line length.
- Refactor
  - Minor internal script cleanup to use in-place list updates, with no behavioral changes.

No user-facing features or behavior changes.

Authors:
  - David Gardner (https://github.com/dagardner-nv)

Approvers:
  - Will Killian (https://github.com/willkill07)

URL: #5

Author: dagardner-nv

.pre-commit-config.yaml

@@ -14,26 +14,20 @@
 # limitations under the License.
 
 repos:
-  - repo: https://github.com/PyCQA/isort
-    rev: 5.12.0
-    hooks:
-      - id: isort
-        args: ["--filter-files", "--settings-file=./pyproject.toml"]
-
-  - repo: https://github.com/PyCQA/flake8
-    rev: 7.0.0
-    hooks:
-      - id: flake8
-        entry: pflake8
-        additional_dependencies: [pyproject-flake8]
-        args: ["--config=./pyproject.toml"]
 
   - repo: https://github.com/google/yapf
     rev: v0.43.0
     hooks:
       - id: yapf
         args: ["-i", "--style", "./pyproject.toml"]
 
+  - repo: https://github.com/astral-sh/ruff-pre-commit
+    rev: v0.12.9
+    hooks:
+      # Run the linter.
+      - id: ruff-check
+        args: [ --fix ]
+
   - repo: https://github.com/astral-sh/uv-pre-commit
     rev: 0.6.2
     hooks:

ci/scripts/copyright.py

@@ -237,7 +237,6 @@ def _main():
     logging.basicConfig(format="%(levelname)s:%(message)s", level=log_level)
 
     ret_val = 0
-    global ExemptFiles
 
     argparser = argparse.ArgumentParser("Checks for a consistent copyright header in git's modified files")
     argparser.add_argument("--update-start-year",
@@ -322,7 +321,7 @@ def _main():
 
     (args, dirs) = argparser.parse_known_args()
     try:
-        ExemptFiles = ExemptFiles + [re.compile(pathName) for pathName in args.exclude]
+        ExemptFiles.extend([re.compile(pathName) for pathName in args.exclude])
     except re.error as re_exception:
         logger.exception("Regular expression error: %s", re_exception, exc_info=True)
         return 1

ci/scripts/gitutils.py

@@ -390,7 +390,6 @@ def get_merge_target():
     str
         Ref name of the target branch
     """
-    #
 
     remote_branch = GithubWrapper.get_pr_target_remote_branch()