fix wasm ci

[michaelkirk]

ureq used to build on wasm, but apparently it never actually worked:
algesten/ureq#667

Now it no longer builds, so I've removed it from CI.

error: the wasm*-unknown-unknown targets are not supported by default, you may need to enable the "js" feature. For more information see: https://docs.rs/getrandom/#webassembly-support
Error:    --> /home/runner/.cargo/registry/src/index.crates.io-6f17d22bba15001f/getrandom-0.2.15/src/lib.rs:342:9
    |
342 | /         compile_error!("the wasm*-unknown-unknown targets are not supported by \
343 | |                         default, you may need to enable the \"js\" feature. \
344 | |                         For more information see: \
345 | |                         https://docs.rs/getrandom/#webassembly-support");
    | |________________________________________________________________________^

error[E0433]: failed to resolve: use of undeclared crate or module `imp`
Error:    --> /home/runner/.cargo/registry/src/index.crates.io-6f17d22bba15001f/getrandom-0.2.15/src/lib.rs:398:9
    |
398 |         imp::getrandom_inner(dest)?;
    |         ^^^ use of undeclared crate or module `imp`