Fix output_env.sh for varying pylint3 output

`pylint3 --version` will output to stderr the status of the config file it's
using. This can be "No config file found" or "Using config file" or nothing.
This means the pylint version may or may not be on the first line.

Therefore this commit changes the filters on the pylint3 version output to first
strip out the config line, and then to select only the pylint line.

Signed-off-by: Simon Butcher <simon.butcher@arm.com>

scripts/output_env.sh

@@ -105,7 +105,7 @@ echo
 print_version "python" "--version" "" "head -n 1"
 echo
 
-print_version "pylint3" "--version" "" "head -n 2" "tail -n 1"
+print_version "pylint3" "--version" "" "sed /^.*config/d" "grep pylint"
 echo
 
 : ${OPENSSL:=openssl}