Fixed Codecov invocation for Windows.
Fixed Codecov invocation for Windows.

Bash for Windows (at least on Travis) doesn't seem to support process
substitution, so we can't use the canonical Codecov Bash invocation.
This commit adds a fix that saves the script to disk first.

Signed-off-by: Jacob Howard <f862f167b85d41b225785c70d70808bc7337c1fe@havoc.io>

havoc-io/mutagen,havoc-io/mutagen