Refactor (#54)

* run `npm ci` instead of `npm install` for PR build

* bump version

* return Promise for test mock

__tests__/main.test.ts

@@ -27,8 +27,8 @@ describe('run', () => {
           path.join(__dirname, 'testdata/audit/success.txt')
         ),
         status: 0,
-        run: (): void => {
-          return
+        run: (): Promise<void> => {
+          return Promise.resolve(void 0)
         },
         foundVulnerability: (): boolean => {
           return false
@@ -60,8 +60,8 @@ describe('run', () => {
           path.join(__dirname, 'testdata/audit/error.txt')
         ),
         status: 1,
-        run: (): void => {
-          return
+        run: (): Promise<void> => {
+          return Promise.resolve(void 0)
         },
         foundVulnerability: (): boolean => {
           return true