Bump actions/checkout from 4 to 7

Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to 7.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v4...v7)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '7'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/backend.yml

@@ -18,7 +18,7 @@ jobs:
       run:
         working-directory: backend
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v7
 
       - name: Set up JDK 25
         uses: actions/setup-java@v4

.github/workflows/frontend.yml

@@ -18,7 +18,7 @@ jobs:
       run:
         working-directory: frontend
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v7
 
       - uses: actions/setup-node@v4
         with:

.github/workflows/infra.yml

@@ -18,7 +18,7 @@ jobs:
       run:
         working-directory: infra
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v7
 
       - uses: actions/setup-node@v4
         with:

.github/workflows/node-services.yml

@@ -28,7 +28,7 @@ jobs:
       run:
         working-directory: ${{ matrix.service }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v7
 
       - uses: actions/setup-node@v4
         with:

.github/workflows/ws-sfu.yml

@@ -18,7 +18,7 @@ jobs:
       run:
         working-directory: ws-sfu
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v7
 
       - uses: dtolnay/rust-toolchain@stable