Remove gradle updater

Has been broken for several months, mailing me daily about failed runs. Needs replacing. See https://github.com/CatimaLoyalty/Android/issues/2525

.github/workflows/gradle-update.yml

@@ -1,33 +0,0 @@
-name: Gradle update
-on:
-  workflow_dispatch:
-  schedule:
-    - cron: '3 6 * * *'
-permissions:
-  actions: none
-  checks: none
-  contents: write
-  deployments: none
-  discussions: none
-  id-token: none
-  issues: none
-  packages: none
-  pages: none
-  pull-requests: write
-  repository-projects: none
-  security-events: none
-  statuses: none
-jobs:
-  gradle-update:
-    runs-on: ubuntu-latest
-    steps:
-    - uses: actions/checkout@v4.2.2
-    - uses: obfusk/gradle-update-action@v3.0.0
-      id: gradle-update
-    - uses: gradle/actions/wrapper-validation@v4
-    - name: Create Pull Request
-      uses: peter-evans/create-pull-request@v7.0.8
-      with:
-        title: "Update Gradle to ${{ steps.gradle-update.outputs.version }}"
-        commit-message: "Update Gradle to ${{ steps.gradle-update.outputs.version }}"
-        branch-suffix: timestamp