chore(Cargo.toml): require qlog v0.15.1 (#2571)

#2512 bumped `qlog` to `v0.15.0`,
but made use of features only available in `qlog` `v0.15.1`. Thus while
using `qlog` `v0.15.0` would be allowed according to Neqo's root
`Cargo.toml`, it would not compile.

This commit increases the `qlog` requirement to `v0.15.1`.

Author: mxinden

Cargo.toml

@@ -33,7 +33,7 @@ enum-map = { version = "2.7", default-features = false }
 enumset = { version = "1.1", default-features = false }
 hex = { version = "0.4", default-features = false }
 log = { version = "0.4", default-features = false }
-qlog = { version = "0.15", default-features = false }
+qlog = { version = "0.15.1", default-features = false }
 quinn-udp = { version = "0.5.11", default-features = false, features = ["direct-log", "fast-apple-datapath"] }
 regex = { version = "1.9", default-features = false }
 static_assertions = { version = "1.1", default-features = false }