Release version 0.19.0

Changelog

• e1b2193 CI: remove golang-ci issue excludes (#207)
• 0ab614d Update README.md
• cf8db95 add /v1/identity/self/describe API
• c99624b add bulk decryption API /v1/key/bulk/decrypt (#210)
• 4983c75 add client-side functionality to detect server APIs
• 696f43d cmd: fix identity command indentation
• 21555fa http: fix /v1/policy/assign API
• 789e1b5 http: restructure API handlers
• 4453475 implement io.WriterTo for iterators
• 54044b7 improve TLS private key / certificate parsing
• 043a116 log: print audit events on a single line
• 4e21298 support +build build tag comments (#215)
• ce5eee7 support go.mod go1.16