chore(ci): don't manually install wasm toolchain (#315)

This is already specified in the toolchain file, so it needn't be
manually installed on CI.

Author: hawkw

.github/workflows/ci.yml

@@ -43,8 +43,6 @@ jobs:
     - uses: actions/checkout@v2
     - name: rust toolchain
       run: rustup show
-    - name: add wasm target
-      run: rustup target add wasm32-unknown-unknown
     - uses: olix0r/cargo-action-fmt@ee1ef42932e44794821dab57ef1bf7a73df8b21f
     - uses: extractions/setup-just@v1
     - name: run just check
@@ -62,8 +60,6 @@ jobs:
     - uses: actions/checkout@v2
     - name: rust toolchain
       run: rustup show
-    - name: add wasm target
-      run: rustup target add wasm32-unknown-unknown
     - uses: olix0r/cargo-action-fmt@ee1ef42932e44794821dab57ef1bf7a73df8b21f
     - uses: extractions/setup-just@v1
     - name: run just clippy