Fix incorrect TypeScript syntax in upgrade callback functions

[Pricstas]

• Fixed incorrect array syntax: [Identifier] → Identifier[]

• Replaced incorrect arrow (=>) syntax for return types:

  • => (version: string, err: Error) → : [string, Error | null]
  • => Error → : Error | null

• Removed unnecessary (version: string) at the end of function definitions

[Pricstas]

Hi @AdityaSripal, @angbrav

Just a friendly reminder about PR #1209: it fixes TypeScript syntax in the upgrade callback functions in UPGRADES.md by:

• Changing [Identifier] to Identifier[]
• Updating arrow return-type syntax to : [string, Error | null] and : Error | null
• Removing unnecessary (version: string) in function definitions

Could you please take a look and approve when you have a moment? Thanks! 🙏