prepare for capnp-v0.21.7 release

Author: dwrensha

capnp/CHANGELOG.md

@@ -1,3 +1,7 @@
+## v0.21.7
+- Resolve type on construction of `Field`. This is expected to improve performance of
+  certain usage patterns of the dynamic API.
+
 ## v0.21.6
 - Fix buffer sizing in `flatten_segments()`. A bug was causing unnecessary allocations in
   `write_message_to_words()` and `write_message_segments_to_words`().

capnp/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 
 name = "capnp"
-version = "0.21.6"
+version = "0.21.7"
 authors = [ "David Renshaw <[email protected]>" ]
 license = "MIT"
 description = "runtime library for Cap'n Proto data encoding"