added pr workflow

.github/workflows/cmor-tables.yaml

@@ -1,24 +1,19 @@
 name: cmor tables
 
-# Controls when the action will run. Workflow runs when manually triggered using the UI
-# or API.
 on:
   workflow_dispatch:
 
   push:
     paths:
       - 'docs/data-request-i4c-merged.csv'
     branches:
-      - "*"
+      - 'main'
 
-
-# A workflow run is made up of one or more jobs that can run sequentially or in parallel
 jobs:
   update-cmor-tables:
-    # The type of runner that the job will run on
     runs-on: ubuntu-latest
-
-    # Steps represent a sequence of tasks that will be executed as part of the job
+    permissions:
+      pull-requests: write
     steps:
     - name: checkout
       uses: actions/checkout@v4
@@ -34,4 +29,17 @@ jobs:
 
     - name: Create tables 
       run: |
-        create-cmor-tables docs/data-request-i4c-merged.csv --coords --output cmor-tables 
+        create-cmor-tables docs/data-request-i4c-merged.csv --coords --output cmor-tables
+
+    - name: Create Pull Request
+        uses: peter-evans/create-pull-request@v6
+        with:
+          commit-message: update cmor tables
+          title: Update CMOR tables
+          body: |
+            Updates cmor tables
+
+            Auto-generated by [create-pull-request][1]
+
+            [1]: https://github.com/peter-evans/create-pull-request
+          branch: cmor-tables-updates