Refactor CI action (rust-lang#1024)

* This separates "setup" from "build"

Author: tedinski

.github/actions/build/action.yml renamed to .github/actions/setup/action.yml

@@ -1,15 +1,19 @@
 # Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 # SPDX-License-Identifier: Apache-2.0 OR MIT
-name: Build Kani
-description: Install dependencies and build kani binaries
+name: Setup Kani Dependencies
 inputs:
   os:
     description: In which Operating System is this running
     required: true
-    default: ubuntu-20.04
 runs:
   using: composite
   steps:
+      # This is unfortunate, but cbmc-viewer currently requires Python >= 3.8
+      - name: Install Python 3.9
+        uses: actions/setup-python@v2
+        with:
+          python-version: '3.9'
+
       - name: Install dependencies
         run: ./scripts/setup/${{ inputs.os }}/install_deps.sh
         shell: bash
@@ -30,10 +34,3 @@ runs:
         run: |
           git submodule update --init --depth 1
         shell: bash
-
-      - name: Build Kani and Kani Library
-        run: |
-          export RUST_BACKTRACE=1
-          cargo build
-        shell: bash
-

.github/workflows/kani.yml

@@ -12,15 +12,17 @@ jobs:
     steps:
       - name: Checkout Kani
         uses: actions/checkout@v2
-      - uses: actions/setup-python@v2
-        with:
-          python-version: '3.9'
 
-      - name: Build Kani
-        uses: ./.github/actions/build
+      - name: Setup Kani Dependencies
+        uses: ./.github/actions/setup
         with:
             os: ${{ matrix.os }}
 
+      - name: Build Kani
+        run: |
+          export RUST_BACKTRACE=1
+          cargo build
+
       - name: Execute Kani regression
         run: ./scripts/kani-regression.sh
 
@@ -32,11 +34,16 @@ jobs:
       - name: Checkout Kani
         uses: actions/checkout@v2
 
-      - name: Build Kani
-        uses: ./.github/actions/build
+      - name: Setup Kani Dependencies
+        uses: ./.github/actions/setup
         with:
             os: ubuntu-20.04
 
+      - name: Build Kani
+        run: |
+          export RUST_BACKTRACE=1
+          cargo build
+
       - name: Install book runner dependencies
         run: ./scripts/setup/install_bookrunner_deps.sh