Try updating CI to fix with newer images (#64)

Author: alexcrichton

.github/workflows/main.yml

@@ -104,7 +104,7 @@ jobs:
         tar xf wasmtime-dev-x86_64-linux-c-api.tar.xz -C c-api --strip-components=1
       if: matrix.os == 'ubuntu-latest'
 
-    - run: sudo apt-get update -y && sudo apt-get install -y gcc-10
+    - run: sudo apt-get update -y && sudo apt-get install -y g++-10
       if: matrix.gcc
 
     # Configure CMake appropriately