Use native Promise versions of fs functions where possible

src/utils/fs.ts

@@ -1,10 +1,11 @@
 import * as fs from 'fs'
+import { promises as fsp } from 'fs'
 import { promisify } from 'util'
 
 export const readFile = promisify(fs.readFile)
-export const writeFile = promisify(fs.writeFile)
-export const copyFile = promisify(fs.copyFile)
+export const writeFile = fsp.writeFile
+export const copyFile = fsp.copyFile
 export const exists = promisify(fs.exists)
-export const unlink = promisify(fs.unlink)
-export const rename = promisify(fs.rename)
-export const mkdir = promisify(fs.mkdir)
+export const unlink = fsp.unlink
+export const rename = fsp.rename
+export const mkdir = fsp.mkdir