rust: Pin hyper 0.14.2

hyper 0.14.3 added an unstable C API, but the changes to enable it
require us to configure cargo with a linker for cross-compilation.
We'll need to figure this out eventually, but for now let's just
pin hyper to a version that doesn't require it.

Cargo.lock

@@ -636,9 +636,9 @@ checksum = "494b4d60369511e7dea41cf646832512a94e542f68bb9c49e54518e0f468eb47"
 
 [[package]]
 name = "hyper"
-version = "0.14.5"
+version = "0.14.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8bf09f61b52cfcf4c00de50df88ae423d6c02354e385a86341133b5338630ad1"
+checksum = "12219dc884514cb4a6a03737f4413c0e01c23a1b059b0156004b23f1e19dccbe"
 dependencies = [
  "bytes",
  "futures-channel",
@@ -1255,10 +1255,11 @@ checksum = "fe0f37c9e8f3c5a4a66ad655a93c74daac4ad00c441533bf5c6e7990bb42604e"
 
 [[package]]
 name = "socket2"
-version = "0.4.0"
+version = "0.3.19"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9e3dfc207c526015c632472a77be09cf1b6e46866581aecae5cc38fb4235dea2"
+checksum = "122e570113d28d773067fab24266b66753f6ea915758651696b6e35e49f88d6e"
 dependencies = [
+ "cfg-if 1.0.0",
  "libc",
  "winapi",
 ]

Cargo.toml

@@ -38,7 +38,7 @@ zcash_proofs = "0.5"
 ed25519-zebra = "2.0.0"
 
 # Metrics
-hyper = { version = "0.14", default-features = false, features = ["server", "tcp", "http1"] }
+hyper = { version = "=0.14.2", default-features = false, features = ["server", "tcp", "http1"] }
 ipnet = "2"
 metrics = "0.14.2"
 metrics-exporter-prometheus = "0.3"