update to solc@0.5.16

update waffle version and fix deprecations

move CI from circle to github actions

.github/workflows/CI.yml

@@ -0,0 +1,33 @@
+name: CI
+
+jobs:
+  test:
+    strategy:
+      matrix:
+        node: ['10.x', '12.x']
+        os: [ubuntu-latest, macOS-latest]
+
+    runs-on: ${{ matrix.os }}
+
+    steps:
+      - uses: actions/checkout@v1
+      - uses: actions/setup-node@v1
+        with:
+          node-version: ${{ matrix.node }}
+
+      - run: npm install -g yarn
+
+      - id: yarn-cache
+        run: echo "::set-output name=dir::$(yarn cache dir)"
+      - uses: actions/cache@v1
+        with:
+          path: ${{ steps.yarn-cache.outputs.dir }}
+          key: ${{ matrix.os }}-yarn-${{ hashFiles('**/yarn.lock') }}
+          restore-keys: |
+            ${{ matrix.os }}-yarn-
+
+      - run: yarn
+
+      - run: yarn lint
+      - run: yarn compile
+      - run: yarn test