Update Go CI tests: MySQL 8.4.2 -> 8.4.3 (#23255)

Make sure Fleet works with the latest MySQL 8.4

.github/workflows/test-go.yaml

@@ -44,7 +44,7 @@ jobs:
       matrix:
         suite: ["integration", "core"]
         os: [ubuntu-latest]
-        mysql: ["mysql:8.0.36", "mysql:8.4.2"] # make sure to update supported versions docs when this changes
+        mysql: ["mysql:8.0.36", "mysql:8.4.3"] # make sure to update supported versions docs when this changes
     continue-on-error: ${{ matrix.suite == 'integration' }} # Since integration tests have a higher chance of failing, often for unrelated reasons, we don't want to fail the whole job if they fail
     runs-on: ${{ matrix.os }}