Make sure a -master suffix is added to built files on master

.drone.yml

@@ -22,7 +22,8 @@ steps:
       - unzip vikunja-frontend-master.zip -d frontend
       - sed -i 's/\/api\/v1//g' frontend/index.html
       - yarn install
-      - export BUILD_NUMBER=master
+      # Make sure that the -master suffix is added to release files
+      - sed -i 's/\$\{version\}/master/g' package.json
       - yarn dist --linux --windows
 
   - name: release

package.json

@@ -18,6 +18,7 @@
   "build": {
     "appId": "io.vikunja.desktop",
     "productName": "Vikunja Desktop",
+    "artifactName": "${productName}-${version}.${ext}",
     "linux": {
       "target": [
         "deb",