Remove obsolete workflows and update-check script

.github/workflows/mirror.yaml

@@ -1,27 +0,0 @@
-name: Mirroring
-
-# yamllint disable-line rule:truthy
-on:
-  push:
-    branches:
-      - master
-      - dev
-
-jobs:
-  mirror_gitee:
-    name: Mirror to Gitee
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v2
-        with:
-          fetch-depth: 0
-      - name: Push to Gitee
-        env:
-          SSH_KEY: ${{ secrets.GITEE_KEY }}
-        run: |
-          mkdir -p ~/.ssh
-          echo "${SSH_KEY}" > ~/.ssh/id_rsa
-          chmod 600 ~/.ssh/id_rsa
-          export GIT_SSH_COMMAND="ssh -o StrictHostKeyChecking=no -l git"
-          git remote add gitee git@gitee.com:shenxn/protonmail-bridge-docker.git
-          git push --tags --force --prune gitee "refs/remotes/origin/*:refs/heads/*"

.github/workflows/update-check.yaml

@@ -1,24 +0,0 @@
-name: update check
-
-on:
-  push:
-    paths:
-      - .github/workflows/update-check.yaml
-      - update-check.py
-  pull_request:
-    paths:
-      - .github/workflows/update-check.yaml
-      - update-check.py
-  schedule:
-  - cron: '0 0 * * *'  # runs everyday at midnight
-
-jobs:
-  check:
-    runs-on: ubuntu-latest
-    steps:
-    - name: Checkout
-      uses: actions/checkout@v4
-      with:
-        token: ${{ secrets.PERSONAL_TOKEN }}
-    - name: Check Update
-      run: python3 update-check.py ${{ github.event_name == 'pull_request' }}