fix: improve compile-time errors if mutually exclusive http-client features are set. (#602)

Author: Byron

etc/check-package-size.sh

@@ -19,14 +19,14 @@ echo "in root: gitoxide CLI"
 (enter git-actor && indent cargo diet -n --package-size-limit 5KB)
 (enter git-pathspec && indent cargo diet -n --package-size-limit 25KB)
 (enter git-refspec && indent cargo diet -n --package-size-limit 25KB)
-(enter git-path && indent cargo diet -n --package-size-limit 15KB)
+(enter git-path && indent cargo diet -n --package-size-limit 20KB)
 (enter git-attributes && indent cargo diet -n --package-size-limit 20KB)
 (enter git-discover && indent cargo diet -n --package-size-limit 25KB)
 (enter git-index && indent cargo diet -n --package-size-limit 50KB)
 (enter git-worktree && indent cargo diet -n --package-size-limit 35KB)
-(enter git-quote && indent cargo diet -n --package-size-limit 5KB)
+(enter git-quote && indent cargo diet -n --package-size-limit 10KB)
 (enter git-revision && indent cargo diet -n --package-size-limit 30KB)
-(enter git-bitmap && indent cargo diet -n --package-size-limit 5KB)
+(enter git-bitmap && indent cargo diet -n --package-size-limit 10KB)
 (enter git-tempfile && indent cargo diet -n --package-size-limit 30KB)
 (enter git-lock && indent cargo diet -n --package-size-limit 20KB)
 (enter git-config && indent cargo diet -n --package-size-limit 120KB)

git-transport/src/client/blocking_io/http/mod.rs

@@ -14,6 +14,9 @@ use crate::{
     Protocol, Service,
 };
 
+#[cfg(all(feature = "http-client-reqwest", feature = "http-client-curl"))]
+compile_error!("Cannot set both 'http-client-reqwest' and 'http-client-curl' features as they are mutually exclusive");
+
 #[cfg(feature = "http-client-curl")]
 mod curl;