fix: pin GitHub Action versions (#612)

Co-authored-by: Eunjae Lee <[email protected]>

packages/shipjs/src/step/setup/CI/addGitHubActions.js

@@ -100,10 +100,10 @@ jobs:
  name: Release
  runs-on: ubuntu-latest
  steps:
- - uses: actions/checkout@master
+ - uses: actions/checkout@v2
  with:
  ref: <%= releaseBranch %>
- - uses: actions/setup-node@master
+ - uses: actions/setup-node@v1
  with:
  registry-url: "https://registry.npmjs.org"
  - run: |
@@ -136,11 +136,11 @@ jobs:
  startsWith(github.event.comment.body, '@shipjs prepare')
  runs-on: ubuntu-latest
  steps:
- - uses: actions/checkout@master
+ - uses: actions/checkout@v2
  with:
  fetch-depth: 0
  ref: <%= baseBranch %>
- - uses: actions/setup-node@master
+ - uses: actions/setup-node@v1
  - run: |
  if [ -f "yarn.lock" ]; then
  yarn install
@@ -197,11 +197,11 @@ jobs:
  schedule_prepare:
  runs-on: ubuntu-latest
  steps:
- - uses: actions/checkout@master
+ - uses: actions/checkout@v2
  with:
  fetch-depth: 0
  ref: <%= baseBranch %>
- - uses: actions/setup-node@master
+ - uses: actions/setup-node@v1
  - run: |
  if [ -f "yarn.lock" ]; then
  yarn install