fix: reworked container architecture (#619)

- Don't set architecture, let Docker host decide it's own platform,
  remove `runtime` dependency and don't show default in `--help`
- Remove most tests, we need to check only once if it works on
  different platform
- Rename `DeleteImage` to `RemoveImage` to conform to existing
  function in `docker` cli, added options to specify `force` and
  `pruneChildren`

cmd/root.go

@@ -6,7 +6,6 @@ import (
 	"os"
 	"path/filepath"
 	"regexp"
-	"runtime"
 	"strings"
 
 	"github.com/nektos/act/pkg/common"
@@ -59,7 +58,7 @@ func Execute(ctx context.Context, version string) {
 	rootCmd.PersistentFlags().StringVarP(&input.secretfile, "secret-file", "", ".secrets", "file with list of secrets to read from (e.g. --secret-file .secrets)")
 	rootCmd.PersistentFlags().BoolVarP(&input.insecureSecrets, "insecure-secrets", "", false, "NOT RECOMMENDED! Doesn't hide secrets while printing logs.")
 	rootCmd.PersistentFlags().StringVarP(&input.envfile, "env-file", "", ".env", "environment file to read and use as env in the containers")
-	rootCmd.PersistentFlags().StringVarP(&input.containerArchitecture, "container-architecture", "", "", "Architecture which should be used to run containers, e.g.: linux/amd64. Defaults to linux/<your machine architecture> [linux/"+runtime.GOARCH+"]. Requires Docker server API Version 1.41+. Ignored on earlier Docker server platforms.")
+	rootCmd.PersistentFlags().StringVarP(&input.containerArchitecture, "container-architecture", "", "", "Architecture which should be used to run containers, e.g.: linux/amd64. If not specified, will use host default architecture. Requires Docker server API Version 1.41+. Ignored on earlier Docker server platforms.")
 	rootCmd.SetArgs(args())
 
 	if err := rootCmd.Execute(); err != nil {