Budibase: SSRF via DNS rebinding in the REST datasource integration

Budibase is an open-source low-code platform. Prior to 3.40.0, packages/backend-core/src/utils/outboundFetch.ts pinned a validated address through a Node agent, but the REST integration used getDispatcher from packages/backend-core/src/utils/fetch.ts, causing undici to ignore that agent and resolve the hostname again. A builder could use DNS rebinding to make packages/server/src/integrations/rest.ts connect to an internal address after a public address passed validation, with full response access and arbitrary REST methods. The fix adds createPinnedLookup support to the undici dispatcher and passes the validated address to custom fetch implementations. This issue is fixed in version 3.40.0.