fix(workflows): add 'Closes #XXX' syntax for automatic issue closing

Author: MarkusNeusinger

.github/workflows/bot-auto-merge.yml

@@ -283,7 +283,9 @@ jobs:
 
           ### Links
           - **Spec:** \`specs/$SPEC_ID.md\`
-          - **Parent Issue:** #$MAIN_ISSUE (closes on merge)
+          - **Parent Issue:** #$MAIN_ISSUE
+
+          Closes #$MAIN_ISSUE
 
           ---
           :robot: *Auto-generated by pyplots CI*" | sed 's|.*/||')
@@ -737,6 +739,8 @@ jobs:
           - **Spec:** \`specs/$SPEC_ID.md\`
           - **Parent Issue:** #$MAIN_ISSUE
 
+          Closes #$MAIN_ISSUE
+
           ---
           :robot: *Auto-generated by pyplots CI*")
 

.github/workflows/gen-library-impl.yml

@@ -200,7 +200,9 @@ jobs:
               **Attempt:** ${{ inputs.attempt }}/3
 
               ## Implementation
-              - \`plots/${{ inputs.library }}/{plot_type}/${{ inputs.spec_id }}/default.py\`"
+              - \`plots/${{ inputs.library }}/{plot_type}/${{ inputs.spec_id }}/default.py\`
+
+              Closes #${{ inputs.sub_issue_number }}"
               ```
 
             ### Important