remove match_labels option

examples/monitoring/src/main.rs

@@ -1,3 +1,4 @@
+use std::collections::HashMap;
 
 use harmony::{
     inventory::Inventory,
@@ -63,7 +64,7 @@ async fn main() {
         target_labels: vec![],
         pod_target_labels: vec![],
         selector: Selector {
-            match_labels: None,
+            match_labels: HashMap::new(),
             match_expressions: vec![MatchExpression {
                 key: "test".to_string(),
                 operator: "In".to_string(),

harmony/src/modules/monitoring/kube_prometheus/types.rs

@@ -154,7 +154,7 @@ pub struct MatchExpression {
 #[serde(rename_all = "camelCase")]
 pub struct Selector {
     //   # label selector for services
-    pub match_labels: Option<HashMap<String, String>>,
+    pub match_labels: HashMap<String, String>,
     pub match_expressions: Vec<MatchExpression>,
 }