fix: Filter bare 'latest' and fix vlatest tag in image discovery

.woodpecker/security-scan.yml

@@ -26,7 +26,8 @@ steps:
           | sed 's/\$${[^}]*:-\([^}]*\)}/\1/g' \
           | sed 's/\$${[^}]*}//g' \
           | sed 's/{{ *[a-z_]* *}}/latest/g' \
-          | grep -v '^$$' | grep -v 'cmd:' | grep -v '{' \
+          | grep -v '^$$' | grep -v '^latest$$' | grep -v 'cmd:' | grep -v '{' \
+          | sed 's/:vlatest/:latest/g' \
           | sort -u > /tmp/images.txt
         echo "Found images to scan:"
         cat /tmp/images.txt