update gitattributes

update incorrect folders and add some other files

.gitattributes

@@ -1,11 +1,11 @@
 # The following files do not need to be in the release tarballs:
+.github/ export-ignore
 .gitattributes export-ignore
 .gitignore export-ignore
-doc/bump_version.sh export-ignore
-doc/release-tasklist export-ignore
+.gitmodules export-ignore
+contrib/release/ export-ignore
 doc/sphinx/ export-ignore
 doc/manual/ export-ignore
-doc/release-tasklist export-ignore
 doc/update_parameters.sh export-ignore
 Jenkinsfile export-ignore
 .zenodo.json export-ignore
@@ -21,4 +21,3 @@ tests/**/*.gnuplot linguist-generated
 
 # The world builder code shouldnt' be counted to ASPECT.
 contrib/world_builder/** linguist-vendored
-