Add newline between header and first changelog entry

Author: internettrans

.changelog/01.txt

@@ -0,0 +1,2 @@
+fix
+Add newline in changelog between header and first item

src/changelog-utils.js

@@ -111,6 +111,7 @@ export async function prepareRelease() {
     newVersion = s.inc(versionBump);
   }
 
+  newChangelogLines.push("");
   newChangelogLines.push(`## ${newVersion}`);
   newChangelogLines.reverse();