Github: Remove commit checker workflow

.github/workflows/commit-checker.yml

@@ -1,45 +0,0 @@
-name: Commit checker
-
-on:
-  pull_request:
-
-jobs:
-  commit-checker:
-    name: Commit checker
-    runs-on: ubuntu-latest
-
-    steps:
-    - name: Checkout
-      uses: actions/checkout@v2
-      with:
-        fetch-depth: 4
-
-    - name: Get pull-request commits
-      run: |
-        set -x
-        # actions/checkout did a merge checkout of the pull-request. As such, the first
-        # commit is the merge commit. This means that on HEAD^ is the base branch, and
-        # on HEAD^2 are the commits from the pull-request. We now check if those trees
-        # have a common parent. If not, we fetch a few more commits till we do. In result,
-        # the log between HEAD^ and HEAD^2 will be the commits in the pull-request.
-        DEPTH=4
-        while [ -z "$(git merge-base HEAD^ HEAD^2)" ]; do
-            git -c protocol.version=2 fetch --no-tags --prune --progress --no-recurse-submodules --deepen=${DEPTH} origin HEAD
-            DEPTH=$(( ${DEPTH} * 4 ))
-        done
-
-        # Just to show which commits we are going to evaluate.
-        git log --oneline HEAD^..HEAD^2
-
-    - name: Checkout commit-checker
-      uses: actions/checkout@v2
-      with:
-        repository: OpenTTD/OpenTTD-git-hooks
-        path: git-hooks
-        ref: master
-
-    - name: Check commits
-      run: |
-        set -x
-        HOOKS_DIR=./git-hooks/hooks GIT_DIR=.git ./git-hooks/hooks/check-commits.sh HEAD^..HEAD^2
-        echo "Commit checks passed"