CI: Pipeline: add write permissions to top script

Signed-off-by: Karol Gugala <kgugala@antmicro.com>

.github/workflows/Automerge.yml

diff --git a/.github/workflows/Automerge.yml b/.github/workflows/Automerge.yml
index 0526350..bc5b487 100644
--- a/.github/workflows/Automerge.yml
+++ b/.github/workflows/Automerge.yml
@@ -28,6 +28,8 @@
   Pipeline:
     if: ${{ !(github.event_name != 'pull_request' && github.actor == 'dependabot[bot]') }}
     uses: ./.github/workflows/Pipeline.yml
+    permissions:
+      contents: write
 
   Action:
     if: ${{ !(github.event_name != 'pull_request' && github.actor == 'dependabot[bot]') }}