[ doc ] Update changelog for v6 release

[ ci ] Avoid tag-scoped cache saves

[ new ] Command line option for printing version info

[ new ] Release Language Server v4 that supports Agda-2.7.0.1, Agda-2…

….6.4.3, and Agda-2.6.3

[ fix ] Add dummy LSP handlers and release Agda v2.7.0.1 Language Ser…

…ver v3

[ fix ] Release Agda v2.7.0.1 Language Server v2

[ new ] Release Agda v2.7.0.1 Language Server v1

[ new ] Release Agda v2.7.0.1 Language Server v0

[ fix ] Set encoding of `stderr` to `utf8`

[ new ] Release v0.2.6.4.0.3