fix: drop prosystem regions, pal is a signal

emulators/prosystem.yml

@@ -34,7 +34,6 @@ notes: |
 files:
   - name: "7800 BIOS (U).rom"
     system: atari-7800
-    region: [north-america]
     required: false
     hle_fallback: true
     size: 4096
@@ -43,7 +42,6 @@ files:
 
   - name: "7800 BIOS (E).rom"
     system: atari-7800
-    region: [europe]
     required: false
     hle_fallback: true
     size: 16384