patch 8.2.2876: configure cannot detect Python 3.10

Problem:    Configure cannot detect Python 3.10.
Solution:   Use sys.version_info. (closes #8233)
diff --git a/src/auto/configure b/src/auto/configure
index 0b423a6..5702a21 100755
--- a/src/auto/configure
+++ b/src/auto/configure
@@ -6673,7 +6673,7 @@
   $as_echo_n "(cached) " >&6
 else
   vi_cv_var_python3_version=`
-          ${vi_cv_path_python3} -c 'import sys; print(sys.version[:3])'`
+          ${vi_cv_path_python3} -c 'import sys; print("{}.{}".format(sys.version_info.major, sys.version_info.minor))'`
 
 fi
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $vi_cv_var_python3_version" >&5