Let's try calculating column diffs

.github/workflows/provider-map-jobs.yml

@@ -80,14 +80,38 @@ jobs:
           with open(geojson_file, 'w') as f:
             json.dump(geojson, f, indent=2)
 
+      - name: Setup yq
+        uses: vegardit/gha-setup-yq@v1
+        with:
+          use-cache: true
+          version: 4.40.5
+
+      - name: Check for column updates
+        id: column-updates
+        run: |
+            curl -O https://raw.githubusercontent.com/cal-itp/data-infra/main/warehouse/models/mart/transit_database/_mart_transit_database.yml
+
+            columns_from_dbt=$(yq '.models[] | select(.name == "dim_mobility_mart_providers") | .columns[].name' _mart_transit_database.yml)
+            columns_from_repo=$(yq '.[].column' src/metadata/providers/dictionary.csv)
+
+            column_diff=$(diff <( printf '%s\n' "$columns_from_dbt" ) <( printf '%s\n' "$columns_from_repo" ))
+
+            echo "column_diff=$column_diff" >> "$GITHUB_OUTPUT"
+
       - name: Create Pull Request
         uses: peter-evans/create-pull-request@v5
         with:
           title: Provider Map Data Auto Update
           body: |
-            It's that time again! The warehouse has delivered new data for us to use.
+            It's that time again! The warehouse has delivered new data for us to use. This is an automatic pull request created by the `provider-map-jobs.yml` workflow; it is triggered via a cron that runs every Sunday at midnight UTC.
+
+            ## Changed Columns
+
+            These are columns that differ between the warehouse and the repository. If you see descrepancies here, please update the `src/metadata/providers/dictionary.csv` file to match the warehouse.
 
-            This is an automatic pull request created by the `provider-map-jobs.yml` workflow. It is triggered by a cron job that runs every Sunday at midnight UTC.
+            ```diff
+            ${{ steps.column-updates.outputs.column_diff }}}
+            ```
           commit-message: Auto-update provider data from warehouse
           add-paths: |
             src/metadata/providers/providers.csv