Remove flake8 from auto-disable dict

flake8 plugin is disabled by default. If it's been enabled in the pylsp
configuration then it's not possible for another plugin to disable it.

The other four plugins (pycodestyle, pyflakes, mccabe, pyls_isort) are all
enabled by default so the ruff plugin can disable them, provided they're not
explicitly enabled in the configuration.

Closes #46

README.md

@@ -19,7 +19,7 @@ There also exists an [AUR package](https://aur.archlinux.org/packages/python-lsp
 
 # Usage
 
-This plugin will disable `flake8`, `pycodestyle`, `pyflakes`, `mccabe` and `pyls_isort` by default.
+This plugin will disable `pycodestyle`, `pyflakes`, `mccabe` and `pyls_isort` by default, unless they are explicitly enabled in the client configuration.
 When enabled, all linting diagnostics will be provided by `ruff`.
 Sorting of the imports through `ruff` when formatting is enabled by default.
 The list of code fixes can be changed via the `pylsp.plugins.ruff.format` option.

pylsp_ruff/plugin.py

@@ -64,12 +64,12 @@
 @hookimpl
 def pylsp_settings():
     log.debug("Initializing pylsp_ruff")
-    # this plugin disables flake8, mccabe, and pycodestyle by default
+    # This plugin disables some enabled-by-default plugins that duplicate Ruff
+    # functionality
     settings = {
         "plugins": {
             "ruff": PluginSettings(),
             "pyflakes": {"enabled": False},
-            "flake8": {"enabled": False},
             "mccabe": {"enabled": False},
             "pycodestyle": {"enabled": False},
             "pyls_isort": {"enabled": False},