ci: Use pre-commit to run linters

Now that pre-commit is added, replace the manual commands for mypy,
isort, and black with equivalent pre-commit commands. This allows us to
avoid duplicating linter arguments. It also allows us to pin the linters
used in CI by way of the .pre-commit-config.yaml file, ensuring
reproducible lint errors.

Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com>

.github/workflows/ci.yml

@@ -23,11 +23,11 @@ jobs:
         run: |
           sudo apt-get update
           sudo apt-get install busybox-static libelf-dev libdw-dev qemu-kvm zstd ${{ matrix.cc == 'clang' && 'libomp-$(clang --version | sed -rn "s/.*clang version ([0-9]+).*/\\1/p")-dev' || '' }}
-          pip install mypy pyroute2
+          pip install pyroute2 pre-commit
       - name: Generate version.py
         run: python setup.py --version
       - name: Check with mypy
-        run: mypy --strict --no-warn-return-any --no-warn-unused-ignores drgn _drgn.pyi
+        run: pre-commit run --all-files mypy
       - name: Build and test with ${{ matrix.cc }}
         run: python setup.py test -K
 
@@ -38,8 +38,6 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v2
       - name: Install dependencies
-        run: pip install black isort
-      - name: Check with black
-        run: black --check --diff .
-      - name: Check with isort
-        run: isort --check --diff .
+        run: pip install pre-commit
+      - name: Run pre-commit hooks
+        run: SKIP=mypy pre-commit run --all-files --show-diff-on-failure