Prepare 3.0.x-devel to become master (#109)

* Refs #20893: Update PR template

Signed-off-by: eduponz <eduardoponz@eprosima.com>

* Refs #20893: Update mirror workflow

Signed-off-by: eduponz <eduardoponz@eprosima.com>

* Refs #20893: Apply Eliana's suggestions

Signed-off-by: eduponz <eduardoponz@eprosima.com>

---------

Signed-off-by: eduponz <eduardoponz@eprosima.com>

.github/pull_request_template.md

@@ -16,7 +16,7 @@
     In case of bug fixes, please provide the list of supported branches where this fix should be also merged.
     Please uncomment following line, adjusting the corresponding target branches for the backport.
 -->
-<!-- @Mergifyio backport 2.13.x 2.10.x 2.6.x -->
+<!-- @Mergifyio backport 2.14.x 2.13.x 2.10.x 2.6.x -->
 
 <!-- If an issue is already opened, please uncomment next line with the corresponding issue number. -->
 <!-- Fixes #(issue) -->
@@ -32,6 +32,11 @@ Related implementation PR:
 
 ## Contributor Checklist
 
+<!--
+    - If any of the elements of the following checklist is not applicable, substitute the checkbox [ ] by _N/A_:
+    - If any of the elements of the following checklist is not fulfilled on purpose, please provide a reason and substitute the checkbox [ ] with ❌: or __NO__:.
+-->
+
 - [ ] Commit messages follow the project guidelines. <!-- External contributors should sign the DCO. ShapesDemo docs developers must also refer to the internal Redmine task. -->
 - [ ] Documentation tests pass locally.
 - [ ] Applicable backports have been included in the description.

.github/workflows/mirror.yml

@@ -3,16 +3,19 @@ on:
   push:
     branches:
       - 'master'
+      - '2.14.x'
 
 jobs:
-  mirror_job:
+  mirror_job_master:
+    if: github.ref == 'refs/heads/master'
     name: Mirror master branch to latest minor branches
     runs-on: ubuntu-latest
     strategy:
       fail-fast: false
       matrix:
         dest_branch:
-          - '2.14.x'
+          - '3.0.x'
+          - '3.x'
     steps:
     - name: Mirror action step
       id: mirror
@@ -21,3 +24,21 @@ jobs:
         github-token: ${{ secrets.GITHUB_TOKEN }}
         source: 'master'
         dest: ${{ matrix.dest_branch }}
+
+  mirror_job_2_x:
+    if: github.ref == 'refs/heads/2.14.x'
+    name: Mirror 2.14.x branch to latest minor branches
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        dest_branch:
+          - '2.x'
+    steps:
+    - name: Mirror action step
+      id: mirror
+      uses: eProsima/eProsima-CI/external/mirror-branch-action@main
+      with:
+        github-token: ${{ secrets.GITHUB_TOKEN }}
+        source: '2.14.x'
+        dest: ${{ matrix.dest_branch }}