Add GitHub Action "Update translations"

This commit implements a GitHub Action to update translation files with the PR automatically created on behalf of "github-actions[bot]", so that manual intervention and inflating activity of a committer is avoided. For now, only catalog templates (POT) files will be updated based on the master branch. When we start publishing translations, we can have the action build them.

Signed-off-by: Suguru Hirahara <acioustick@noreply.codeberg.org>

.github/workflows/update-translations.yml

@@ -0,0 +1,52 @@
+# SPDX-FileCopyrightText: 2024 Suguru Hirahara
+#
+# SPDX-License-Identifier: AGPL-3.0-or-later
+
+---
+name: Update translations
+
+on:  # yamllint disable-line rule:truthy
+  push:
+    branches:
+      - master
+    paths:  # See include_patterns on conf.py
+      - 'docs/*.md'
+      - 'i18n/README.md'
+      - '*.md'
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  update:
+    if: github.repository == 'spantaleev/matrix-docker-ansible-deploy'
+    name: Update translations
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+
+      - uses: actions/setup-python@v6
+        with:
+          python-version: '3.13'
+
+      # Setting up recommended prerequisites
+      # See: i18n/README.md
+      - uses: astral-sh/setup-uv@v7
+      - uses: extractions/setup-just@v3
+
+      # TODO: optimize when we start publishing translations and integrate a Weblate instance
+      - name: Update translation catalog templates (POT) files
+        run: just --justfile i18n/justfile extract-translation-templates
+
+      - name: Create Pull Request
+        uses: peter-evans/create-pull-request@v8.1.0
+        with:
+          author: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>  # Same as committer
+          body: This is an automatic pull request to update translation files.
+          branch: create-pull-request/i18n
+          commit-message: Automatic translations update
+          delete-branch: true
+          labels: docs
+          sign-commits: true
+          title: Automatic translations update