v0.4.0 - 2021-02

• feat: use structured logging for exceptions (#278)
• feat: convert storage Pub/Sub events (#273)
• feat: how-to guide using Cloud Build for builder (#267)
• chore: update to pack v0.17.0 (#263)
• feat: implement code for Cloud Spanner tutorial (#239)
• feat: implement code for Cloud Bigtable tutorial (#238)
• doc: this library is now published in vcpkg (#237)
• feat: fix compilation problems on MSVC (#233)
• doc: new guide to deploy Pub/Sub function to Cloud Run (#234)
• doc: new guide to deploy on Cloud Run (#232)
• doc: describe how to create a Docker image (#212)
• doc: describe how to run a local server (#209)
• We implemented many other examples, but this changelog is
  too long already.