* fix!: change timing for initialization
fix#109fix#59
This fixes problems below.
* Auto-validation feature is called at Neovim starting.
- → Now it starts at `:Telescope frecency` called at the first time.
* `frecency.setup()` is called every when `:Telescope frecency` is
called.
- → Now it is called only once.
* `telescope.setup()` calls `frecency.new()` and it reads the database.
This causes time in executing `init.lua`.
- → Now it reads the database lazily. It reads at the first time when
needed.
* test: change logic to initialize config
* test: make Neovim version newer in CI
