Unable to update https://github.com/tower-rs/tower?branch=std-future

[UkonnRa]

Using branch = std-future and an error found:

error: failed to load source for a dependency on `tower-service`

Caused by:
  Unable to update https://github.com/tower-rs/tower?branch=std-future

Caused by:
  failed to find branch `std-future`

Caused by:
  cannot locate local branch 'std-future'; class=Reference (4); code=NotFound (-3)

[LucioFranco]

Reference https://github.com/tower-rs/tower-grpc/pull/208#issuecomment-535052437