ci: pin Python to 3.12 in build workflow to fix PyO3 compatibility

- Add actions/setup-python@v5.3.0 step to pin Python version to 3.12
- Fixes PyO3 build failure where pydantic-core was attempting to build
  against Python 3.14, which exceeds PyO3 v0.24.1's maximum supported
  version (3.13)
- Also fix docstring linter error in airbyte/mcp/__init__.py (D412)

Resolves CI failures in Build and/or Publish and Run Linters workflows.

Co-Authored-By: AJ Steers <aj@airbyte.io>

Author: devin-ai-integration[bot]

.github/workflows/pypi_publish.yml

@@ -15,6 +15,9 @@ jobs:
     - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
       with:
         fetch-depth: 0
+    - uses: actions/setup-python@0b93645e9fea7318ecaed2b359559ac225c90a2b # v5.3.0
+      with:
+        python-version: '3.12'
     - uses: hynek/build-and-inspect-python-package@c52c3a4710070b50470d903818a7b25115dcd076 # v2.13.0
 
   publish:

airbyte/mcp/__init__.py

@@ -173,7 +173,6 @@
 - Is writable by the user account running the MCP server.
 
 Note:
-
 - In rare cases, your agent may not be able to find `uv` or `uvx` if they are not in the system
   `PATH` or if the agent has a stale `PATH` value. In these cases, you can use `which uvx` from
   your own terminal to discover the full path to the `uvx` binary, and then provide the full path