proxy: v2.164.0 (#7142)

This release changes the default allocator (on linux/x86_64) to be
`jemalloc`. In tests, jemalloc proves to use less memory without
noticeable impacts on CPU utilization or latency.

This change also includes dependency updates, including an update of
Rust to v1.56.0.

---

* build(deps): bump tower from 0.4.9 to 0.4.10 (linkerd/linkerd2-proxy#1320)
* Adopt Rust edition 2021 (linkerd/linkerd2-proxy#1295)
* Use jemalloc (linkerd/linkerd2-proxy#1321)
* Disable incremental compilation in CI (linkerd/linkerd2-proxy#1322)
* build(deps): bump h2 from 0.3.6 to 0.3.7 (linkerd/linkerd2-proxy#1324)
* build(deps): bump http-body from 0.4.3 to 0.4.4 (linkerd/linkerd2-proxy#1325)
* build(deps): bump hyper from 0.14.13 to 0.14.14 (linkerd/linkerd2-proxy#1326)

.proxy-version

@@ -1 +1 @@
-v2.163.0
+v2.164.0