ReadMe.md: replace GitCoin with LB #3955

Job	Run time
linux-github--dotnet-and-mono	4m 11s
linux-vanilla--stockdotnet6-and-newmono	6m 24s
linux-github--dotnet-and-newmono	7m 49s
linux-vanilla--newmono-only	8m 58s
linux-vanilla--stockdotnet6-and-stockmono	7m 20s
linux-vanilla--stockdotnet6-only	5m 35s
linux-vanilla--stockmono-only	6m 3s
macOS--dotnet6-and-mono	17m 55s
macOS--dotnet6-only	6m 33s
macOS--mono-only	14m 27s
windows--dotnet6-and-legacyFramework	6m 33s
windows--dotnet6-only	6m 36s
windows--legacyFramework-only	27m 52s
conventions	1m 17s
snap_pkg	6m 39s
snap_pkg_beta	8m 19s
	2h 22m 31s

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