Add CHANGELOG for #5347

.changesets/fix_skewer_boyfriend_forum_sleigh.md

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+### Update `apollo-compiler` for two small improvements ([PR #5347](https://github.com/apollographql/router/pull/5347))
+
+Updated our underlying `apollo-rs` dependency on our `apollo-compiler` crate to bring in two nice improvements:
+
+- **Fix validation performance bug
+
+  Adds a cache in fragment spread validation, fixing a situation where validating a query
+  with many fragment spreads against a schema with many interfaces could take multiple
+  seconds to validate.
+
+- **Remove ariadne byte/char mapping
+
+  Generating JSON or CLI reports for apollo-compiler diagnostics used a translation layer
+  between byte offsets and character offsets, which cost some computation and memory
+  proportional to the size of the source text. The latest version of `ariadne` allows us to
+  remove this translation.
+
+By [@goto-bus-stop](https://github.com/goto-bus-stop) in https://github.com/apollographql/router/pull/5347