message: meta: Update 7.8.1 changelog
  Add a few entries that made it into 7.8.1 after we merged
diff: - fix(nextjs): Add default `distDir` value back into `index.server.ts` (#5479)
  - fix(node): Add conditions to TracingHandler.startTransaction (#5485)
  +- fix(node): Adjust Express URL parameterization for array routes (#5495)
  - fix(node): Adjust Express URL parameterization for RegEx routes (#5483)
  +- fix(node): Check if router exists before it is instrumented (#5502)
  - fix(node): Correctly handle Windows paths when resolving module name (#5476)
  +- fix(node): Ensure that self._handler exists before calling it in LinkedErrors (#5497)
  - ref(tracing): Simplify sample_rate serialization for DSC (#5475)
  ## 7.8.0
  