Add migration changelog type (#2243)

Author: Mirko-von-Leipzig

.github/pull_request_template.md

@@ -25,7 +25,7 @@ reason    = "Internal change only."
 ```
 
 Allowed scopes: rpc, protocol, docs, node, network-monitor, ntx-builder, prover, validator, internal, general
-Allowed impacts: breaking, added, changed, fixed, removed, deprecated
+Allowed impacts: breaking, migration, added, changed, fixed, removed, deprecated
 -->
 
 ```toml

xtask/src/changelog.rs

@@ -55,6 +55,7 @@ enum Scope {
 #[serde(rename_all = "kebab-case")]
 enum Impact {
     Breaking,
+    Migration,
     Added,
     Changed,
     Fixed,
@@ -296,6 +297,19 @@ description = "Added a bootstrap command."
         verify_pr_body(&body).unwrap();
     }
 
+    #[test]
+    fn accepts_migration_impact() {
+        let body = valid_body(
+            r#"[[entry]]
+scope       = "node"
+impact      = "migration"
+description = "Added a storage migration for node databases."
+"#,
+        );
+
+        verify_pr_body(&body).unwrap();
+    }
+
     #[test]
     fn accepts_validator_and_internal_scopes() {
         let body = valid_body(