bump mysql dependency (#365)

Author: jxs

refinery_core/Cargo.toml

@@ -32,7 +32,7 @@ walkdir = "2.3.1"
 rusqlite = { version = ">= 0.23, <= 0.33", optional = true }
 postgres = { version = ">=0.17, <= 0.19", optional = true }
 tokio-postgres = { version = ">= 0.5, <= 0.7", optional = true }
-mysql = { version = ">= 21.0.0, <= 25", optional = true, default-features = false, features = ["minimal"] }
+mysql = { version = ">= 21.0.0, <= 26", optional = true, default-features = false, features = ["minimal"] }
 mysql_async = { version = ">= 0.28, <= 0.35", optional = true, default-features = false, features = ["minimal"] }
 tiberius = { version = ">= 0.7, <= 0.12", optional = true, default-features = false }
 tokio = { version = "1.0", optional = true }