update project.properties in MPL too

Author: robin-aws

.github/actions/polymorph_codegen/action.yml

@@ -66,6 +66,13 @@ runs:
         git pull
         git submodule update --init --recursive
 
+    - name: Update top-level project.properties file in MPL
+      if: inputs.update-and-regenerate-mpl == 'true'
+      shell: bash
+      working-directory: submodules/MaterialProviders
+      run: |
+        make generate_properties_file
+
     # Update the project.properties file so that we pick up the right runtimes etc.,
     # in cases where inputs.dafny is different from the current value in that file.
     - name: Generate smithy-dafny-project.properties file