chore: remove rsasig feature from the default

Author: junkurihara

httpsig-hyper/Cargo.toml

@@ -13,7 +13,7 @@ rust-version.workspace = true
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [features]
-default = ["blocking", "rsasig"]
+default = ["blocking"]
 blocking = ["futures/executor"]
 rsasig = ["httpsig/rsasig"]