ci: use main rust-toolchain action

Author: palkan

Diff for: .github/workflows/build.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v4
-    - uses: actions-rust-lang/setup-rust-toolchain@v1
+    - uses: actions-rust-lang/setup-rust-toolchain@main
       with:
         toolchain: 1.74.0
     - uses: ruby/setup-ruby@v1