Pin libc to older version for Rust 1.56 (#102)

Author: lambda-fairy

.github/workflows/main.yml

@@ -24,6 +24,9 @@ jobs:
         uses: dtolnay/rust-toolchain@master
         with:
           toolchain: ${{ matrix.rust }}
+      - name: Override libc version (Rust 1.56 only)
+        if: matrix.rust == '1.56'
+        run: cargo update -p libc --precise 0.2.163
       - name: Setup cache
         uses: Swatinem/rust-cache@v2
       - name: Test (no features)