Auto merge of #7377 - rust-lang:dependabot/cargo/hex-0.4, r=alexcrichton

Update hex requirement from 0.3 to 0.4

Updates the requirements on [hex](https://github.com/KokaKiwi/rust-hex) to permit the latest version.
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Cargo.toml

@@ -35,7 +35,7 @@ fs2 = "0.4"
 git2 = "0.10.0"
 git2-curl = "0.11.0"
 glob = "0.3.0"
-hex = "0.3"
+hex = "0.4"
 home = "0.5"
 humantime = "1.2.0"
 ignore = "0.4.7"