title: cargo-generate install fail on Ubuntu 20.04
body: <p>Trying to install cargo-generate on Ubuntu 20.04.1 LTS, first it complained about ssl, installed libssl with this command <code>sudo apt-get install -y libssl-dev</code> but now getting the error below.</p>
  <p>How can I install cargo-generate on Ubuntu 20.04?</p>
  <pre><code>rustc --version
  rustc 1.49.0 (e1884a8e3 2020-12-29)
  
  cargo --version
  cargo 1.49.0 (d00d64df9 2020-12-05)
  
  cargo install cargo-generate
  .....
     Compiling crypto-hash v0.3.4
     Compiling crates-io v0.31.1
     Compiling git2 v0.13.17
     Compiling git2-curl v0.14.1
     Compiling cargo v0.46.1
          error[E0283]: type annotations needed
             --&gt; /home/username/.cargo/registry/src/github.com-1ecc6299db9ec823/cargo-0.46.1/src/cargo/util/config/de.rs:471:63
              |
          471 |                 seed.deserialize(Tuple2Deserializer(1i32, env.as_ref()))
              |                                                           ----^^^^^^--
              |                                                           |   |
              |                                                           |   cannot infer type for type parameter `T` declared on the trait `AsRef`
              |                                                           this method call resolves to `&amp;T`
              |
              = note: cannot satisfy `std::string::String: AsRef&lt;_&gt;`
          
          error: aborting due to previous error
          
          For more information about this error, try `rustc --explain E0283`.
          error: failed to compile `cargo-generate v0.5.1`, intermediate artifacts can be found at `/tmp/cargo-installtb5LHS`
          
          Caused by:
            could not compile `cargo`
          
          To learn more, run the command again with --verbose.
  </code></pre>