ci: update go versions to 1.19, 1.20

Since go 1.20 is released, only 1.20.x and 1.19.x are supported, and
all the older versions are not:

 - go 1.18.x is not supported since Go 1.20 release in Feb 2023;
 - go 1.17.x is not supported since Go 1.19 release in Aug 2022;
 - go 1.16.x is not support since Go 1.18 release in May 2022.

Signed-off-by: Kir Kolyshkin <[email protected]>

Author: kolyshkin

.github/workflows/test.yml

@@ -15,7 +15,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        go-version: [1.16.x, 1.17.x, 1.18.x]
+        go-version: [1.19.x, 1.20.x]
         libseccomp: ["v2.3.3", "v2.4.3", "v2.5.4", "HEAD"]
 
     steps: