deps: update actions/checkout digest to b4ffde6 (#696)

Author: renovate-bot

.github/workflows/downstream-dependencies.yaml

@@ -18,7 +18,7 @@ jobs:
  - java-storage
  - java-pubsub
  steps:
- - uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4
+ - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4
  - uses: actions/setup-java@v3
  with:
  distribution: zulu
@@ -31,7 +31,7 @@ jobs:
  flatten-plugin-check:
  runs-on: ubuntu-latest
  steps:
- - uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4
+ - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4
  - uses: actions/setup-java@v3
  with:
  distribution: zulu

.github/workflows/downstream-maven-plugins.yaml

@@ -24,7 +24,7 @@ jobs:
  - clirr # clirr-maven-plugin
  - javadoc # maven-javadoc-plugin
  steps:
- - uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4
+ - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4
  - uses: actions/setup-java@v3
  with:
  distribution: zulu
@@ -41,7 +41,7 @@ jobs:
  repo:
  - java-bigtable
  steps:
- - uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4
+ - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4
  - uses: actions/setup-java@v3
  with:
  distribution: temurin