docs/conf.py: Enable imgmath_embed for Sphinx >=5.3.0

The imgmath extension had a regression reported at [1].

This regression is related to the new option: imgmath_embed added
in Sphinx 5.2.0. Enabling the option is an workaround to the issue.

The regression has been fixed since Sphinx 6.0.1, but it should be
reasonable to keep the option afterwards.

Link: [1] sphinx-doc/sphinx#10944
Signed-off-by: Akira Yokosawa <akiyks@gmail.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>

Documentation/conf.py

@@ -143,6 +143,9 @@ def have_command(cmd):
 if load_imgmath:
     extensions.append("sphinx.ext.imgmath")
     math_renderer = 'imgmath'
+    # workaround Sphinx issue #10944
+    if (major, minor) >= (5, 3):
+        imgmath_embed = True
 else:
     math_renderer = 'mathjax'