Remove go 1.19 from CI

.github/workflows/test.yml

@@ -14,7 +14,7 @@ jobs:
       image: darthsim/imgproxy-ci:202311211816
     strategy:
       matrix:
-        go-version: ["1.21.x", "1.20.x", "1.19.x"]
+        go-version: ["1.21.x", "1.20.x"]
         vips-version: ["8.15", "8.14", "8.13"]
     steps:
       - name: Checkout