add check to not build if no changes made to src/

Author: markzegarelli

netlify.toml

@@ -4,6 +4,9 @@
   # ignore = "git log -1 --pretty=%B | ( ! grep -q '\[netlify\-build\]' )"
   # Ignore if [netlify-ignore] is present
 
+  # Don't build if there are no changes to src/
+  ignore = "git diff --quiet HEAD^ HEAD src/"
+
 [context.deploy-preview]
   command = "yarn develop"
   ignore = "./scripts/ignore.sh"