feat: fix empty map merge after mergo bump

since mergo had been bumped to 0.3.9 an environment value like:
```
affinity: {}
```
was not merged properly (not merged at all) instead it threw an error
that it cannot find the key "affinity" in the environment values even
though it was outputted in debug output as read in properly.

pkg/state/envvals_loader.go

@@ -73,7 +73,7 @@ func (ld *EnvironmentValuesLoader) LoadEnvironmentValues(missingFileHandler *str
 			if err != nil {
 				return nil, err
 			}
-			if err := mergo.Merge(&result, &vals, mergo.WithOverride); err != nil {
+			if err := mergo.Merge(&result, &vals, mergo.WithOverride, mergo.WithOverwriteWithEmptyValue); err != nil {
 				return nil, fmt.Errorf("failed to merge %v: %v", m, err)
 			}
 		}