CI: ignore netrc warnings caused by Kas

As of oe-core ba391d3, hashserv lookups will use authentication from the
.netrc file.  However, Kas will write invalid netrc files with comments,
which causes bitbake to emit warnings.

This has been fixed in Kas in e700729 but until Kas 4.3.2 is released we
can ignore this warning specifically when checking the logs.

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Jon Mason <jon.mason@arm.com>

ci/check-warnings

@@ -7,7 +7,7 @@ set -e -u
 
 LOGFILE=$1
 
-LINES=$(grep --invert-match "attempting MIRRORS if available" $LOGFILE | wc -l)
+LINES=$(sed -e "/attempting MIRRORS if available/d" -e "/Error parsing .*netrc:/d" $LOGFILE | wc -l)
 if test "$LINES" -ne 0; then
     echo ==============================
     echo The build had warnings/errors: