v0.10.21

Changelog

b142d5d README: tighten up the readme (#2574)
a1f5902 README: update readme with github community health files (#2573)
1510383 cli: update for v0.10.20 (#2572)
6330d73 k8s: when injecting labels to match selectors, only update existing values (#2577)
99fda28 klog: ignore too old resource version warnings (#2575)
9483862 scritps: remove protocc (#2585)
41c73d4 starkit: allow setState func to return error (#2579)
c1b0ddd tiltfile: add flags.set_resources (#2578)
82a7940 webui: fix upgrade notification text (#2583)