ci: Use go 1.19 (dexidp#2791)

The go module and Dockerfile moved to 1.19 in d33e994
The nix environment moved to go 1.19 in cf572e9

Signed-off-by: Daniel Lipovetsky <dlipovetsky@d2iq.com>

.github/workflows/ci.yaml

@@ -64,7 +64,7 @@ jobs:
       - name: Set up Go
         uses: actions/setup-go@v3
         with:
-          go-version: 1.18
+          go-version: 1.19
 
       - name: Checkout code
         uses: actions/checkout@v3