fixed wrong env syntax

droppy/docker-compose.yml

@@ -9,6 +9,6 @@ services:
       - ./data/config:/config
       - ${data}:/files
     environment:
-      - uid:${uid}
-      - gid:${gid}
+      - uid=${uid}
+      - gid=${gid}
     restart: unless-stopped

rfidac/docker-compose.yml

@@ -7,5 +7,7 @@ services:
     devices:
       - '/dev/input/event0:/dev/input/event0'
     environment:
-      - mpd_host:${mpd_host}
-      - mpd_files:${mpd_files}
+      - mpd_host=${mpd_host}
+      - mpd_folder=${mpd_folder}
+    volumes:
+      - ../mopidy/data/mopidy/music:/music