Travis build fails when installing cargo-generate

[AndrewPomorski]

Describe the Bug

When running a build on travis using the default .travis.yml file, the build fails on before script :

 before_script:
      - (test -x $HOME/.cargo/bin/cargo-install-update || cargo install cargo-update)

Steps to Reproduce

1. Generate a wasm-pack-template project with
   cargo generate --git https://github.com/rustwasm/wasm-pack-template.git --name my-project

2. Set up a build on travis CI

3. push to master, the build will fail

https://travis-ci.org/github/AndrewPomorski/wasm-game-of-life/jobs/726136106/config

Additional info

The error message from Travis build server:

error[E0283]: type annotations needed
  --> /home/travis/.cargo/registry/src/gitproxy.zycloud.tk-1ecc6299db9ec823/liquid-0.15.0/src/compiler/parser.rs:88:80
   |
88 |                     Token::Identifier(ref x) => indexes.push(Index::with_key(x.as_ref())),
   |                                                                                ^^^^^^ cannot infer type for struct `std::string::String`
   |
   = note: cannot satisfy `std::string::String: std::convert::AsRef<_>`
error: aborting due to previous error
For more information about this error, try `rustc --explain E0283`.
error: could not compile `liquid`.
To learn more, run the command again with --verbose.
warning: build failed, waiting for other jobs to finish...
error: failed to compile `cargo-generate v0.2.2`, intermediate artifacts can be found at `/tmp/cargo-installcA84wZ`

Expected Behavior

The build should pass without having to reconfigure travis.

Actual Behavior

Build fails