Force nvm v0.39 also for test tasks

This is complementary to #6 and refs #7 to revert

.github/workflows/moodle-ci.yml

@@ -242,7 +242,9 @@ jobs:
           echo $(cd ci/bin; pwd) >> $GITHUB_PATH
           echo $(cd ci/vendor/bin; pwd) >> $GITHUB_PATH
           sudo locale-gen en_AU.UTF-8
-          echo "NVM_DIR=$HOME/.nvm" >> $GITHUB_ENV
+          # echo "NVM_DIR=$HOME/.nvm" >> $GITHUB_ENV
+          # Install nvm v0.39 (workaround for https://github.com/moodlehq/moodle-plugin-ci/issues/309).
+          curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.39.7/install.sh | bash
 
       - name: Install tool plugin
         if: ${{ inputs.requires-tool-plugin == true }}