Disable CI runs for stable / beta

.github/workflows/ci.yml

@@ -5,19 +5,7 @@ on: [push, pull_request]
 jobs:
   build:
     runs-on: ubuntu-latest
-
-    strategy:
-      matrix:
-        toolchain:
-          - stable
-          - beta
-          - nightly
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
-        with:
-          toolchain: ${{ matrix.toolchain }}
-      - uses: actions-rs/cargo@v1
-        with:
-          command: build
-          args: --release
+      - uses: actions/checkout@v3
+      - uses: dtolnay/rust-toolchain@nightly
+      - run: cargo test --release

src/lib.rs

@@ -1,4 +1,5 @@
 //! Load MagicaVoxel .vox files into Rust
+#![feature(let_chains)]
 
 extern crate byteorder;
 #[cfg(test)]
@@ -216,8 +217,6 @@ pub mod placeholder {
 
 #[cfg(test)]
 mod tests {
-    use std::collections::HashMap;
-
     use super::*;
     use avow::vec;