api: Fix GitHubError / InvalidUri(InvalidFormat)

[maflcko]

This fixes a symbol name and a bug:

thread panicked at 'called `Result::unwrap()` on an `Err` value: GitHubError(Uri { source: InvalidUri(InvalidFormat), backtrace: Backtrace(   0: <snafu::backtrace_shim::Backtrace as snafu::GenerateImplicitDat
a>::generate
             at /root/.cargo/registry/src/github.com-1ecc6299db9ec823/snafu-0.7.4/src/backtrace_shim.rs:15:19
      snafu::GenerateImplicitData::generate_with_source
             at /root/.cargo/registry/src/github.com-1ecc6299db9ec823/snafu-0.7.4/src/lib.rs:1152:9
   1: <octocrab::error::UriSnafu as snafu::IntoError<octocrab::error::Error>>::into_error
             at /root/.cargo/git/checkouts/octocrab-800d493a1be2acf4/50f3f8f/src/error.rs:23:10
   2: <core::result::Result<T,E> as snafu::ResultExt<T,E>>::context
             at /root/.cargo/registry/src/github.com-1ecc6299db9ec823/snafu-0.7.4/src/lib.rs:697:31
   3: octocrab::Octocrab::parameterized_uri
             at /root/.cargo/git/checkouts/octocrab-800d493a1be2acf4/50f3f8f/src/lib.rs:1103:19
   4: octocrab::Octocrab::get_with_headers::{{closure}}
             at /root/.cargo/git/checkouts/octocrab-800d493a1be2acf4/50f3f8f/src/lib.rs:1126:32
   5: <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll
             at /build/rustc-Oic09u/rustc-1.65.0+dfsg0ubuntu1/library/core/src/future/mod.rs:91:19
   6: octocrab::Octocrab::get::{{closure}}
             at /root/.cargo/git/checkouts/octocrab-800d493a1be2acf4/50f3f8f/src/lib.rs:1073:55
   7: <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll
             at /build/rustc-Oic09u/rustc-1.65.0+dfsg0ubuntu1/library/core/src/future/mod.rs:91:19
   8: octocrab::api::issues::ListCommentsBuilder::send::{{closure}}
             at /root/.cargo/git/checkouts/octocrab-800d493a1be2acf4/50f3f8f/src/api/issues.rs:716:50

[XAMPPRocky]

Thank you for your PR!