config: update am_check_pymod.m4

Problem: The am_check_pymod.m4 file in flux-accounting is out-of-date
compared to flux-core's, which results in a failure to run ./configure
with --enable-docs set and the introduction of man pages to
flux-accounting.

Update am_check_pymod.m4 to match flux-core's.

config/am_check_pymod.m4

@@ -15,12 +15,15 @@ except:
         sys.exit(0)
 sys.exit(0)"], [prog="
 import sys
-from distutils.version import LooseVersion, StrictVersion
+try:
+    from distutils.version import StrictVersion as Version
+except ModuleNotFoundError:
+    from packaging.version import Version
 import $1
 if not $2:
     sys.exit(1)
 "])
-if $PYTHON -c "$prog" 1>&AC_FD_CC 2>&AC_FD_CC
+if $PYTHON -c "$prog" 1>&AS_MESSAGE_LOG_FD 2>&AS_MESSAGE_LOG_FD
   then
     eval "py_cv_mod_$py_mod_var=yes"
   else