chore(linux): Ignore buildtools in keyman-config tarball
chore(linux): Ignore buildtools in keyman-config tarball

`buildtools/build-langtags.py` gets executed before creating the
source tarball, so we don't need it in the source package. Excluding
it reduces confusion because the files it requires are not found
in the source package.

tavultesoft/keymanweb,tavultesoft/keymanweb