fix: add @jest/transform as an optional peer dependency

[G-Rath]

Summary

ts-jest/src/types.ts

Line 1 in edef16e

import type { TransformedSource, Transformer, TransformOptions } from '@jest/transform'

The above import means when using TypeScript there is a dependency on @jest/transform which is currently not expressed, making Yarn Berry unhappy when using the PnP linker.

From what I understand, specifying this dependency as an optional peer dependency should resolve this.

Test plan

Does this PR introduce a breaking change?

• Yes
• No

Other information