Add mirror workflow (#76)

Signed-off-by: EduPonz <[email protected]>

.github/workflows/mirror.yml

@@ -0,0 +1,22 @@
+# .github/workflows/mirror.yml
+on:
+  push:
+    branches:
+      - 'main'
+jobs:
+  mirror_job:
+    runs-on: ubuntu-latest
+    name: Mirror main branch to compatible minor version branches
+    strategy:
+      fail-fast: false
+      matrix:
+        dest_branch:
+          - '1.4.x'
+    steps:
+    - name: Mirror action step
+      id: mirror
+      uses: eProsima/eProsima-CI/external/mirror-branch-action@v0
+      with:
+        github-token: ${{ secrets.GITHUB_TOKEN }}
+        source: 'main'
+        dest: ${{ matrix.dest_branch }}