Update packages

[timlrx]

• Add integration test for remark-gfm
• Update unified js and remark/rehype packages (fix https://github.com/contentlayerdev/contentlayer/issues/558)
• Fix changeset configuration (https://github.com/contentlayerdev/contentlayer/pull/622)
• Support next 14 and resolve manual override (https://github.com/contentlayerdev/contentlayer/issues/575)
• Update opentelemetry (As proposed in https://github.com/contentlayerdev/contentlayer/pull/519 updating the packages may fix https://github.com/contentlayerdev/contentlayer/issues/506. Can't replicate the issue but the older package works for me with the recent opentelemetry versions without overrides)
• Changed package name from contentlayer to contentlayer2