Use hashes for file names to fix cache-related issues after updates

https://github.com/iqb-berlin/testcenter-frontend/issues/212

CHANGELOG.md

 # Changelog
 
+## 12.1.8
+* (#212) fix cache-related issues after updates
+
 ## 12.1.7
 * (#385) Fix Bug: If testee is on the please-enter-code-screen and group-monitor moves him to the same block, 
   it should become unlocked (but didn't).

docker/Dockerfile

@@ -20,7 +20,7 @@ RUN npx webdriver-manager update --versions.chrome=`google-chrome --product-vers
 
 COPY . /app
 
-RUN ng build --prod=true --output-path=dist
+RUN ng build --prod=true --output-path=dist --output-hashing all
 
 EXPOSE 4200
 

package.json

@@ -15,7 +15,7 @@
   "scripts": {
     "ng": "ng",
     "start": "ng serve",
-    "build": "ng build",
+    "build": "ng build --output-hashing all",
     "test": "ng test  --watch=false",
     "lint": "ng lint",
     "e2e": "ng e2e",