Raise the workspace reqwest floor to 0.12.20

The feature list names system-proxy, which older 0.12 releases do not
have.

Author: findolor

Cargo.toml

@@ -17,7 +17,7 @@ clap = { version = "4.2.5", features = ["cargo", "derive"] }
 once_cell = "1.17.1"
 # rustls instead of the default native-tls/OpenSSL backend, so TLS follows
 # rustls-webpki's trust decisions. Keeps the other default features.
-reqwest = { version = "0.12.5", default-features = false, features = [
+reqwest = { version = "0.12.20", default-features = false, features = [
   "json",
   "rustls-tls-native-roots",
   "charset",