Ignore coverage for non-existent source type

lib/modules/manager/pep621/processors/uv.ts

@@ -61,6 +61,7 @@ export class UvProcessor implements PyProjectProcessor {
         // Using `packageName` as it applies PEP 508 normalization, which is
         // also applied by uv when matching a source to a dependency.
         const depSource = uv.sources?.[dep.packageName];
+        /* istanbul ignore else  */
         if (depSource) {
           // Dependency is pinned to a specific source.
           dep.depType = depTypes.uvSources;