fix: remove unused os import from SkillsManager.ts

Author: hannesrudolph

src/services/skills/SkillsManager.ts

@@ -1,6 +1,5 @@
 import * as fs from "fs/promises"
 import * as path from "path"
-import * as os from "os"
 import * as vscode from "vscode"
 import matter from "gray-matter"