chore: fix bumpVersion type check (#23906)

lib/modules/manager/maven/update.spec.ts

@@ -49,7 +49,7 @@ describe('modules/manager/maven/update', () => {
     it('does not bump version if pom.xml has no version', () => {
       const { bumpedContent } = pomUpdater.bumpPackageVersion(
         minimumContent,
-        undefined,
+        '',
         'patch'
       );
 

lib/modules/manager/nuget/update.spec.ts

@@ -67,11 +67,7 @@ describe('modules/manager/nuget/update', () => {
     });
 
     it('does not bump version if extract found no version', () => {
-      const { bumpedContent } = bumpPackageVersion(
-        minimumContent,
-        undefined,
-        'patch'
-      );
+      const { bumpedContent } = bumpPackageVersion(minimumContent, '', 'patch');
 
       expect(bumpedContent).toEqual(minimumContent);
     });