Fix: don't use default locale when uppercasing region code

SampleApps/Psibot/app/src/main/java/ca/psiphon/PsiphonTunnel.java

@@ -555,7 +555,7 @@ public class PsiphonTunnel extends Psi.PsiphonProvider.Stub {
                 region = defaultLocale.getCountry();
             }
         }
-        return region.toUpperCase();
+        return region.toUpperCase(Locale.US);
     }
 
     //----------------------------------------------------------------------------------------------

SampleApps/TunneledWebView/app/src/main/java/ca/psiphon/PsiphonTunnel.java

@@ -401,6 +401,6 @@ public class PsiphonTunnel extends Psi.PsiphonProvider.Stub {
                 region = defaultLocale.getCountry();
             }
         }
-        return region.toUpperCase();
+        return region.toUpperCase(Locale.US);
     }
 }