chore: remove dead code from src/utils/imghdr_stub.py

Removed the `test()` and `testall()` functions and the `if __name__ == "__main__":` block which were used for manual testing and are not needed by the codebase.
This improves maintainability and readability by focusing the module on its core functionality.

Co-authored-by: PR0M3TH3AN <[email protected]>

src/utils/imghdr_stub.py

@@ -168,53 +168,3 @@ def test_exr(h, f):
 
 
 tests.append(test_exr)
-
-
-# --------------------
-# Small test program
-# --------------------
-
-
-def test():  # pragma: no cover - only used for manual testing
-    import sys
-
-    recursive = 0
-    if sys.argv[1:] and sys.argv[1] == "-r":
-        del sys.argv[1:2]
-        recursive = 1
-    try:
-        if sys.argv[1:]:
-            testall(sys.argv[1:], recursive, 1)
-        else:
-            testall(["."], recursive, 1)
-    except KeyboardInterrupt:
-        sys.stderr.write("\n[Interrupted]\n")
-        sys.exit(1)
-
-
-def testall(list, recursive, toplevel):  # pragma: no cover - only for manual use
-    import sys
-    import os
-
-    for filename in list:
-        if os.path.isdir(filename):
-            print(filename + "/:", end=" ")
-            if recursive or toplevel:
-                print("recursing down:")
-                import glob
-
-                names = glob.glob(os.path.join(glob.escape(filename), "*"))
-                testall(names, recursive, 0)
-            else:
-                print("*** directory (use -r) ***")
-        else:
-            print(filename + ":", end=" ")
-            sys.stdout.flush()
-            try:
-                print(what(filename))
-            except OSError:
-                print("*** not found ***")
-
-
-if __name__ == "__main__":  # pragma: no cover - manual run
-    test()