Feat: Support macOS and Windows, migrate JavaScript to TypeScript (#32)

- Support macOS and Windows (Close #24 )
- Refactoring
  - Error handling
  - TypeScript
- Prettier (Close #29 )
- GHA: Add upload-artifact step for test coverage
- deps: Install husky

src/index.ts

@@ -0,0 +1,38 @@
+import * as core from '@actions/core';
+import * as exec from '@actions/exec';
+import getLatestVersion from './get-latest-version';
+import installer from './installer';
+
+// most @actions toolkit packages have async methods
+async function run() {
+  const dump = async () => {
+    // Show version
+    await exec.exec('hugo version');
+    await exec.exec('go version');
+    await exec.exec('git --version');
+  };
+
+  try {
+    const hugoVersion: string = core.getInput('hugo-version');
+    console.log(`Hugo version: ${hugoVersion}`);
+
+    if (hugoVersion === '' || hugoVersion === 'latest') {
+      getLatestVersion().then(
+        async function(latestVersion): Promise<void> {
+          await installer(latestVersion);
+          await dump();
+        },
+        function(error) {
+          core.setFailed(error);
+        }
+      );
+    } else {
+      await installer(hugoVersion);
+      await dump();
+    }
+  } catch (error) {
+    core.setFailed(error.message);
+  }
+}
+
+run();