settings: Remove version fields (#33372)

This cleans up our settings to not include any `version` fields, as we
have an actual settings migrator now.

This PR removes `language_models > anthropic > version`,
`language_models > openai > version` and `agent > version`.

We had migration paths in the code for a long time, so in practice
almost everyone should be using the latest version of these settings.


Release Notes:

- Remove `version` fields in settings for `agent`, `language_models >
anthropic`, `language_models > openai`. Your settings will automatically
be migrated. If you're running into issues with this open an issue
[here](https://github.com/zed-industries/zed/issues)

Cargo.lock

@@ -110,18 +110,11 @@ dependencies = [
 name = "agent_settings"
 version = "0.1.0"
 dependencies = [
- "anthropic",
  "anyhow",
  "collections",
- "deepseek",
  "fs",
  "gpui",
  "language_model",
- "lmstudio",
- "log",
- "mistral",
- "ollama",
- "open_ai",
  "paths",
  "schemars",
  "serde",