Tidy detection of JSON files due to missing call to File.recognizes that...

Tidy detection of JSON files due to missing call to File.recognizes that checks against the output of file(1) which I think (!) was also causing us to attempt to parse almost every file using json.loads. Whoops.

diffoscope/comparators/json.py

@@ -38,10 +38,13 @@ except ImportError:  # noqa
 
 class JSONFile(File):
     DESCRIPTION = "JSON files"
-    FILE_TYPE_RE = re.compile(r"JSON data")  # Requires file 5.35+
+    FILE_TYPE_RE = re.compile(r"^JSON data")  # Requires file 5.35+
 
     @classmethod
     def recognizes(cls, file):
+        if not super().recognizes(file):
+            return False
+
         with open(file.path, "rb") as f:
             try:
                 file.parsed = json.loads(