refactor: use vim.system instead of pleanry (#85)

* refactor!: migrate to vim.system

* refactor(gotests): use vim.system

* refactor(iferr): use vim.system

* refactor(impl): use vim.system

* refactor(installer): use vim.system and add sync mode

* test: fix gotests' tests

* refactor(struct_tags): use vim.system

* chore(ci): install all deps explicitly

* refactor(installer)!: add sync as an option

* docs: update readme

lua/gopher/config.lua

@@ -33,6 +33,10 @@ local default_config = {
   ---@type number
   log_level = vim.log.levels.INFO,
 
+  -- timeout for running commands
+  ---@type number
+  timeout = 2000,
+
   -- user specified paths to binaries
   ---@class gopher.ConfigCommand
   commands = {