[ci] Fix typo in error annotation workflow command

Signed-off-by: Alex Jones <alex.jones@lowrisc.org>

Author: AlexJones0

ci/scripts/check-ascii.sh

@@ -86,7 +86,7 @@ git ls-files | \
     grep -v "${suff_re}" | \
     env LC_ALL=C xargs grep -d skip -P '[^\0-\x7f]' >"$TMPFILE" || true
 if [ -s "$TMPFILE" ]; then
-    echo -n ":error::"
+    echo -n "::error::"
     echo "One or more files have unexpected non-ASCII text:"
     cat "$TMPFILE"
     exit 1