Skip calling a binary (JxrDecApp) from libjxr which is used for tests.
We don't package libjxr and it seems to be dead upstream (last commit in 2017).

--- a/src/calibre/utils/img.py
+++ b/src/calibre/utils/img.py
@@ -131,8 +131,6 @@
     i = QImage()
     if not imageops.load_from_data_without_gil(i, data):
         q = what(None, data)
-        if q == 'jxr':
-            return load_jxr_data(data)
         ba = QByteArray(data)
         buf = QBuffer(ba)
         buf.open(QIODevice.OpenModeFlag.ReadOnly)
@@ -886,15 +884,6 @@
     despeckle_image(img)
     remove_borders_from_image(img)
     image_to_data(img, fmt='GIF')
-    p = subprocess.Popen(
-        [get_exe_path('JxrDecApp'), '-h'],
-        creationflags=subprocess.DETACHED_PROCESS if iswindows else 0,
-        stdout=subprocess.PIPE,
-    )
-    raw, _ = p.communicate()
-    p.wait()
-    if b'JPEG XR Decoder Utility' not in raw:
-        raise SystemExit('Failed to run JxrDecApp')
 
 
 # }}}