- add gh action to build the application

- add `dep` script to makefile (update carthage dependency)

- change carthage build -> carthage update in gh action

.github/workflows/build.yaml

@@ -0,0 +1,36 @@
+name: Build the application
+
+on:
+  push:
+    branches:
+      - master
+
+jobs:
+  build:
+    runs-on: macos-latest
+
+    steps:
+      - uses: actions/checkout@master
+
+      - name: Fetch dependencies from cache
+        id: cache
+        uses: actions/cache@v2
+        with:
+          path: Carthage
+          key: ${{ runner.os }}-carthage-${{ hashFiles('**/Cartfile.resolved') }}
+          restore-keys: |
+            ${{ runner.os }}-carthage-
+
+      - name: Install carthage dependencies
+        if: steps.cache.outputs.cache-hit != 'true'
+        run: carthage update --platform macOS
+
+      - name: Build application
+        if: success()
+        run: |
+          xcodebuild \
+            -scheme Stats \
+            -destination 'platform=OS X,arch=x86_64' \
+            -configuration Release \
+            CODE_SIGN_IDENTITY="" \
+            CODE_SIGNING_REQUIRED=NO