Fix some new Clippy lints

[rubdos]

Not entirely sure about this (cca447a):

commit cca447a69d9a5cb1b86714dc1d88856e96b5d9cd
Author: Ruben De Smet <[email protected]>
Date:   Fri Jul 5 16:05:16 2024 +0200

    Fix fallback to never type clippy warning

diff --git a/libsignal-service/src/account_manager.rs b/libsignal-service/src/account_manager.rs
index 14c6242c2..0ca2abad9 100644
--- a/libsignal-service/src/account_manager.rs
+++ b/libsignal-service/src/account_manager.rs
@@ -580,7 +580,7 @@ impl<Service: PushService> AccountManager<Service> {
         }
 
         self.service
-            .put_json(
+            .put_json::<(), _>(
                 Endpoint::Service,
                 "/v1/accounts/name",
                 &[],

The return value is inferred by Rust Analyzer to be !, but that's obviously skipping over the happy-path. I'm 99% sure that the type system infers the Ok-type to be () in Rust 2018 (which is what we're running), but from the clippy warning, it seems that it'll change to ! (as RA says too), so we have to make this type explicit.