Use nix to install awscli (#140)

.github/workflows/cron.yml

@@ -29,9 +29,15 @@ jobs:
       with:
         fetch-depth: 0
 
+    - name: Installing Nix
+      uses: cachix/install-nix-action@v8
+
+    - name: Installing awscli
+      run: |
+        nix-env -iA nixpkgs.awscli
+
     - name: Check for latest evaluation in ${{ matrix.channel }} channel
       run: |
-        sudo apt-get install -y awscli
         if [ "${{ matrix.channel }}" = "unstable" ]; then
           RELEASE=$(aws s3 ls --no-sign-request "$S3_URL/" | grep "/$" | cut -d" " -f29 | sort | tail -1 | sed 's|/||')
         else
@@ -40,13 +46,6 @@ jobs:
         aws s3 cp --no-sign-request "$S3_URL/$RELEASE/src-url" ./
         echo "::set-env name=EVAL_ID::$(cat src-url | cut -c30-)"
 
-    - name: Cache ${{ matrix.channel }} channel builds
-      id: eval-cache
-      uses: actions/cache@v2
-      with:
-        path: ./eval-cache
-        key: eval-cache-${{ env.EVAL_ID }}
-
     - name: Download latest builds for ${{ matrix.channel }} channel (if needed)
       if: steps.eval-cache.outputs.cache-hit != 'true'
       run: |
@@ -54,8 +53,12 @@ jobs:
         cp ./src-url ./eval-cache/
         curl -H "Content-Type: application/json" "$(cat ./eval-cache/src-url)/builds" -o ./eval-cache/builds.json
 
-    - name: Installing Nix
-      uses: cachix/install-nix-action@v8
+    - name: Cache ${{ matrix.channel }} channel builds
+      id: eval-cache
+      uses: actions/cache@v2
+      with:
+        path: ./eval-cache
+        key: eval-cache-${{ env.EVAL_ID }}
 
     - name: Installing NixFlakes
       run: |