fix: handle env-vars case sensitive (#1493)

Closes #1488

pkg/model/workflow.go

@@ -458,16 +458,8 @@ func (s *Step) String() string {
 }
 
 // Environments returns string-based key=value map for a step
-// Note: all keys are uppercase
 func (s *Step) Environment() map[string]string {
-	env := environment(s.Env)
-
-	for k, v := range env {
-		delete(env, k)
-		env[strings.ToUpper(k)] = v
-	}
-
-	return env
+	return environment(s.Env)
 }
 
 // GetEnv gets the env for a step