Fix compilation error

Fix the following warning/error:

    ../app/src/cli.c:2158:17: warning: a label can only be part of a
    statement and a declaration is not a statement [-Wpedantic]

With some compilers, this is an error rather than a pedantic warning.

Refs <#2256 (comment)>

app/src/cli.c

@@ -2154,14 +2154,15 @@ parse_args_with_getopt(struct scrcpy_cli_args *args, int argc, char *argv[],
                     return false;
                 }
                 break;
-            case OPT_ORIENTATION:
+            case OPT_ORIENTATION: {
                 enum sc_orientation orientation;
                 if (!parse_orientation(optarg, &orientation)) {
                     return false;
                 }
                 opts->display_orientation = orientation;
                 opts->record_orientation = orientation;
                 break;
+            }
             case OPT_RENDER_DRIVER:
                 opts->render_driver = optarg;
                 break;