feat: allow selecting the nightly toolchain

.forgejo/workflows/test.yml

@@ -14,17 +14,17 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
-      - name: Test ${{ toolchain}}
+      - name: Test ${{ toolchain }}
         uses: https://git.kemitix.net/kemitix/rust@next
         with:
-          args: ${{toolchain}} cargo test
+          args: ${{ toolchain }} cargo test
 
       - name: Build ${{ toolchain }}
         uses: https://git.kemitix.net/kemitix/rust@next
         with:
           args: ${{ toolchain }} cargo build
 
-      - name: Run ${{ toolchain }}
+      - name: Run
         uses: https://git.kemitix.net/kemitix/rust@next
         with:
-          args: ${{ toolchain }} cargo run
+          args: cargo run