With the latest fern, syslog can be a config option instead of a build flag

Cargo.toml

@@ -11,7 +11,8 @@ publish = false
 build = "build.rs"
 
 [features]
-enable_syslog = ["syslog", "fern/syslog-4"]
+# Empty to keep compatibility, prefer to set USE_SYSLOG=true
+enable_syslog = []
 
 [dependencies]
 # Web framework for nightly with a focus on ease-of-use, expressibility, and speed.
@@ -40,7 +41,7 @@ serde_json = "1.0.39"
 
 # Logging
 log = "0.4.6"
-fern = "0.5.7"
+fern = { version = "0.5.8", features = ["syslog-4"] }
 syslog = { version = "4.0.1", optional = true }
 
 # A safe, extensible ORM and Query builder
@@ -54,7 +55,7 @@ libsqlite3-sys = { version = "0.12.0", features = ["bundled"] }
 ring = { version = "0.13.5", features = ["rsa_signing"] }
 
 # UUID generation
-uuid = { version = "0.7.2", features = ["v4"] }
+uuid = { version = "0.7.4", features = ["v4"] }
 
 # Date and time library for Rust
 chrono = "0.4.6"