fix(ci): use nvm 0.39.7 to overcome regression issue

this is a temporary fix (#126)

.github/workflows/moodle-ci.yml

@@ -61,7 +61,8 @@ 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
+          # Install nvm v0.39.7 (temp workaround for issue moodlehq/moodle-plugin-ci#309).
+          curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.39.7/install.sh | bash
 
       - name: Install moodle-plugin-ci
         run: moodle-plugin-ci install --plugin ./plugin --db-host=127.0.0.1