chore(CI/CD): let's not install mustache engine anymore

Author: mfranzke

.github/workflows/continuous-integration.yml

@@ -17,7 +17,6 @@ jobs:
       - name: Setup the project
         run: |
           yarn run setup
-          npx lerna add @pattern-lab/engine-mustache --scope=@pattern-lab/core
           npx lerna add @pattern-lab/engine-handlebars --scope=@pattern-lab/core
           npx lerna add @pattern-lab/engine-underscore --scope=@pattern-lab/core
           npx lerna add @pattern-lab/engine-liquid --scope=@pattern-lab/core