[ci] Change check-wasm job to use ubuntu-20.04 runner

.github/workflows/cont_integration.yml

@@ -113,7 +113,7 @@ jobs:
   
   check-wasm:
     name: Check WASM
-    runs-on: ubuntu-16.04
+    runs-on: ubuntu-20.04
     env:
       CC: clang-10
       CFLAGS: -I/usr/include
@@ -130,7 +130,7 @@ jobs:
           key: ${{ runner.os }}-cargo-${{ github.job }}-${{ hashFiles('**/Cargo.toml','**/Cargo.lock') }}
         # Install a recent version of clang that supports wasm32
       - run: wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add - || exit 1
-      - run: sudo apt-add-repository "deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-10 main" || exit 1
+      - run: sudo apt-add-repository "deb http://apt.llvm.org/focal/ llvm-toolchain-focal-10 main" || exit 1
       - run: sudo apt-get update || exit 1
       - run: sudo apt-get install -y libclang-common-10-dev clang-10 libc6-dev-i386 || exit 1
       - name: Set default toolchain