Update Dart.gitignore
Update Dart.gitignore

add the `.pub/` directory, and change the `packages` filter to match sub-folders.
szymanskirafal/gitignore,szymanskirafal/gitignore,bruennijs/ise.cppworkshop,szymanskirafal/gitignore,bruennijs/ise.cppworkshop,chhsieh/gitTest_1,chhsieh/helloworld,bruennijs/ise.cppworkshop