fix(ci): upgrade deprecated actions, fix Go version

production-deploy.yml:
- Replace actions-rs/toolchain@v1 with dtolnay/rust-toolchain@stable
- Upgrade actions/cache@v3 -> @v4
- Upgrade github/codeql-action/upload-sarif@v2 -> @v3
- Upgrade actions/upload-artifact@v3 -> @v4

backend-ci.yml:
- Upgrade Go 1.22 -> 1.23 to match go.mod (1.23.8)

Addresses audit findings A08: deprecated actions and outdated Go version.

Co-authored-by: Cursor <cursoragent@cursor.com>

.github/workflows/backend-ci.yml

@@ -24,7 +24,7 @@ jobs:
       - name: Set up Go
         uses: actions/setup-go@v5
         with:
-          go-version: "1.22"
+          go-version: "1.23"
           cache: true
 
       - name: Download deps

veza-stream-server/.github/workflows/production-deploy.yml

@@ -22,14 +22,12 @@ jobs:
       uses: actions/checkout@v4
 
     - name: Setup Rust
-      uses: actions-rs/toolchain@v1
+      uses: dtolnay/rust-toolchain@stable
       with:
-        toolchain: stable
         components: rustfmt, clippy
-        override: true
 
     - name: Cache dependencies
-      uses: actions/cache@v3
+      uses: actions/cache@v4
       with:
         path: |
           ~/.cargo/registry
@@ -119,7 +117,7 @@ jobs:
         output: 'trivy-results.sarif'
 
     - name: Upload Trivy scan results
-      uses: github/codeql-action/upload-sarif@v2
+      uses: github/codeql-action/upload-sarif@v3
       with:
         sarif_file: 'trivy-results.sarif'
 
@@ -220,7 +218,7 @@ jobs:
         k6 run --out json=websocket-test-results.json tests/load/websocket-test.js
 
     - name: Upload test results
-      uses: actions/upload-artifact@v3
+      uses: actions/upload-artifact@v4
       with:
         name: load-test-results
         path: "*-test-results.json"