[CI] Set rust toolchain to nightly-2020-10-06

Author: 0yi0

.github/workflows/.autobuild.yml

@@ -21,6 +21,10 @@ jobs:
     container:
       image: secondstate/substrate-ssvm
 
+    strategy:
+      matrix:
+        toolchain: ['nightly-2020-10-06']
+
     # Steps represent a sequence of tasks that will be executed as part of the job
     steps:
     # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
@@ -31,4 +35,7 @@ jobs:
       run: |
         ln -sf /root/.rustup $HOME/
         ln -sf /root/.cargo $HOME/
-        cargo build --release
+        rustup toolchain install ${{ matrix.toolchain }}
+        rustup target add wasm32-unknown-unknown --toolchain ${{ matrix.toolchain }}
+        rustup default ${{ matrix.toolchain }}
+        cargo build --release