[.github/workflow/rust.yml] Add docker credentials to avoid rate limit

To avoid errors such
```
Error toomanyrequests: You have reached your pull rate limit. You may increase the limit by authenticating and upgrading: https://www.docker.com/increase-rate-limit
```

we should add login to our Scylladb docker hub

Adding it

.github/workflows/authenticate_test.yml

@@ -25,9 +25,13 @@ jobs:
         ports:
           - 9042:9042
         options: --health-cmd "cqlsh --username cassandra --password cassandra --debug" --health-interval 5s --health-retries 30
+      env:
+        DOCKERHUB_USERNAME: ${{ secrets.DOCKERHUB_USERNAME }}
+        DOCKERHUB_TOKEN: ${{ secrets.DOCKERHUB_TOKEN }}
     steps:
     - uses: actions/checkout@v3
     - name: Update rust toolchain
       run: rustup update
     - name: Run tests
       run: RUST_LOG=trace cargo test --verbose authenticate_superuser -- custom_authentication --ignored
+

.github/workflows/book.yml

@@ -25,6 +25,9 @@ jobs:
         ports:
           - 9042:9042
         options: --health-cmd "cqlsh --debug scylladb" --health-interval 5s --health-retries 10
+      env:
+        DOCKERHUB_USERNAME: ${{ secrets.DOCKERHUB_USERNAME }}
+        DOCKERHUB_TOKEN: ${{ secrets.DOCKERHUB_TOKEN }}
     steps:
     - uses: actions/checkout@v3
     - name: Update rust toolchain

.github/workflows/cassandra.yml

@@ -24,6 +24,9 @@ jobs:
     - name: Setup 3-node Cassandra cluster
       run: |
         docker compose -f test/cluster/cassandra/docker-compose.yml up -d --wait
+      env:
+        DOCKERHUB_USERNAME: ${{ secrets.DOCKERHUB_USERNAME }}
+        DOCKERHUB_TOKEN: ${{ secrets.DOCKERHUB_TOKEN }}
       # A separate step for building to separate measuring time of compilation and testing
     - name: Update rust toolchain
       run: rustup update

.github/workflows/rust.yml

@@ -26,6 +26,9 @@ jobs:
       run: |
         sudo sh -c "echo 2097152 >> /proc/sys/fs/aio-max-nr"
         docker compose -f test/cluster/docker-compose.yml up -d --wait
+      env:
+        DOCKERHUB_USERNAME: ${{ secrets.DOCKERHUB_USERNAME }}
+        DOCKERHUB_TOKEN: ${{ secrets.DOCKERHUB_TOKEN }}
     - name: Update rust toolchain
       run: rustup update
     - name: Print rustc version

.github/workflows/tls.yml

@@ -30,6 +30,9 @@ jobs:
           --health-retries 10
     env:
       working-directory: ./scylla
+      DOCKERHUB_USERNAME: ${{ secrets.DOCKERHUB_USERNAME }}
+      DOCKERHUB_TOKEN: ${{ secrets.DOCKERHUB_TOKEN }}
+
     steps:
     - uses: actions/checkout@v3
     - name: Update rust toolchain