Fix recent new compiler warnings (#711)

Author: Sushisource

core/src/abstractions.rs

@@ -221,7 +221,10 @@ impl OwnedMeteredSemPermit {
 }
 
 #[derive(Debug)]
-pub(crate) struct UsedMeteredSemPermit(OwnedMeteredSemPermit);
+pub(crate) struct UsedMeteredSemPermit(
+    // Field isn't read, but we need to hold on to it.
+    #[allow(dead_code)] OwnedMeteredSemPermit,
+);
 
 macro_rules! dbg_panic {
   ($($arg:tt)*) => {

core/src/worker/workflow/wft_extraction.rs

@@ -21,7 +21,11 @@ pub(super) struct WFTExtractor {}
 
 pub(super) enum WFTExtractorOutput {
     NewWFT(PermittedWFT),
-    FetchResult(PermittedWFT, Arc<HistfetchRC>),
+    FetchResult(
+        PermittedWFT,
+        // Field isn't read, but we need to hold on to it.
+        #[allow(dead_code)] Arc<HistfetchRC>,
+    ),
     NextPage {
         paginator: HistoryPaginator,
         update: HistoryUpdate,