fix jsonrpc version type to honor JSON-RPC protocol spec

[estin]

Hi!

I'm trying pylyzer with Helix editor. This fix allow to use pylyzer.

In specification https://www.jsonrpc.org/specification#response_object

jsonrpc
  A String specifying the version of the JSON-RPC protocol. MUST be exactly "2.0".

to enable pylyzer in helix: ~/.config/helix/languages.toml

[language-server]
pylyzer = { command = "pylyzer", args = ["--server"] }

[[language]]
name = "python"
language-servers = [ "pylyzer" ]
auto-format = true
# TODO: pyls needs utf-8 offsets
indent = { tab-width = 4, unit = "    " }

[mtshiba]

Thank you!

Soon I will release a new pylyzer version.