Changelog for PR #4038: Port to apollo-compiler 1.0 beta

.changesets/fix_simon_compiler_1_0.md

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+### Port to apollo-compiler 1.0 beta ([PR #4038](https://github.com/apollographql/router/pull/4038))
+
+Version 1.0 is a near-complete rewrite of `apollo-compiler`.
+Using it in the Router unblocks a lot of upcoming work.
+
+As a more immediate benefit, some serialization-related bugs including 
+[Issue #3541](https://github.com/apollographql/router/issues/3541) are fixed.
+The representation of GraphQL documents in previous compiler versions was immutable.
+When modifying a query (such as to remove `@authenticated` fields from an unauthenticated request)
+the Router would build a new data structure with `apollo-encoder`, serialize it, and reparse it.
+`apollo-compiler`` 1.0 allows mutating a document in-place, skipping the serialization step entirely.
+
+By [@SimonSapin](https://github.com/SimonSapin) in https://github.com/apollographql/router/pull/4038