Bump actions/checkout from 1 to 2.3.4

Bumps [actions/checkout](https://github.com/actions/checkout) from 1 to 2.3.4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v1...v2.3.4)

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/chromatic.yml

@@ -26,7 +26,7 @@ jobs:
     test:
         runs-on: ubuntu-latest
         steps:
-            - uses: actions/checkout@v1
+            - uses: actions/checkout@v2.3.4
             - uses: guardian/actions-setup-node@main
             - uses: actions/cache@v2
               with:

.github/workflows/nodejs.yml

@@ -13,7 +13,7 @@ jobs:
         runs-on: ubuntu-latest
 
         steps:
-            - uses: actions/checkout@v1
+            - uses: actions/checkout@v2.3.4
             - uses: guardian/actions-setup-node@main
             - uses: actions/cache@v2
               with:

.github/workflows/pr-deployment.yml

@@ -12,7 +12,7 @@ jobs:
         runs-on: ubuntu-latest
 
         steps:
-            - uses: actions/checkout@v2
+            - uses: actions/checkout@v2.3.4
             - uses: guardian/actions-setup-node@main
             - uses: actions/cache@v2
               with:

.github/workflows/snyk.yml

@@ -14,7 +14,7 @@ jobs:
                 node-version: [12.x]
 
         steps:
-            - uses: actions/checkout@v2
+            - uses: actions/checkout@v2.3.4
             - name: Run Snyk to check for vulnerabilities
               uses: snyk/actions/node@master
               env: