Fix compile warning on pdf config constants

Signed-off-by: trivernis <trivernis@protonmail.com>

Cargo.lock

@@ -1908,7 +1908,7 @@ checksum = "c111b5bd5695e56cffe5129854aa230b39c93a305372fdbb2668ca2394eea9f8"
 
 [[package]]
 name = "snekdown"
-version = "0.30.2"
+version = "0.30.3"
 dependencies = [
  "asciimath-rs",
  "base64 0.12.3",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "snekdown"
-version = "0.30.2"
+version = "0.30.3"
 authors = ["trivernis <trivernis@protonmail.com>"]
 edition = "2018"
 license-file = "LICENSE"

src/references/configuration/keys.rs

@@ -1,3 +1,5 @@
+#![allow(unused)]
+
 pub const BIB_REF_DISPLAY: &str = "bib-ref-display";
 pub const META_LANG: &str = "language";