refactor(ci): remove mypy (#1371)

* refactor(ci): remove mypy

* fix(ci): restore 'type: ignore' comment for st_birthtime property

.github/workflows/mypy.yaml

@@ -1,36 +0,0 @@
-# SPDX-FileCopyrightText: (c) TagStudio Contributors
-# SPDX-License-Identifier: GPL-3.0-only
----
-name: MyPy
-
-on: [push, pull_request]
-
-jobs:
-  mypy:
-    name: Run MyPy
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout repo
-        uses: actions/checkout@v4
-
-      - name: Setup reviewdog
-        uses: reviewdog/action-setup@v1
-        with:
-          reviewdog_version: latest
-
-      - name: Setup Python
-        uses: actions/setup-python@v5
-        with:
-          python-version: "3.12"
-          cache: pip
-
-      - name: Install Python dependencies
-        run: |
-          python -m pip install --upgrade uv
-          uv pip install --system .[mypy]
-
-      - name: Execute MyPy
-        uses: tsuyoshicho/action-mypy@v4
-        with:
-          github_token: ${{ secrets.GITHUB_TOKEN }}
-          fail_on_error: true