changelog: update for 0.34.0-rc3 (tendermint#5240)

changelog: rc0/33.8 (tendermint#5222)

add dates to changelog

prepare 0.33.7 release (tendermint#5202)

Release v0.34.0-rc2

Tagged v0.32.13-rc1

changelog: tweak 0.33.6 entry

Tagged v0.34.0 version for developer testing

prepare v0.33.5 RC2

test: revert Go 1.13→1.14 bump

Since we support 1.13 and above, let's use that as a baseline for tests.