Clippy 1.49.0 updates and dht persistence test fix (#2156)

## Issue Addressed

`test_dht_persistence` failing

## Proposed Changes

Bind `NetworkService::start` to an underscore prefixed variable rather than `_`.  `_` was causing it to be dropped immediately

This was failing 5/100 times before this update, but I haven't been able to get it to fail after updating it

Co-authored-by: realbigsean <seananderson33@gmail.com>

consensus/state_processing/src/per_block_processing/signature_sets.rs

@@ -44,10 +44,10 @@ impl From<BeaconStateError> for Error {
 }
 
 /// Helper function to get a public key from a `state`.
-pub fn get_pubkey_from_state<'a, T>(
-    state: &'a BeaconState<T>,
+pub fn get_pubkey_from_state<T>(
+    state: &BeaconState<T>,
     validator_index: usize,
-) -> Option<Cow<'a, PublicKey>>
+) -> Option<Cow<PublicKey>>
 where
     T: EthSpec,
 {

consensus/state_processing/src/per_block_processing/tests.rs

@@ -391,7 +391,7 @@ fn invalid_attestation_wrong_justified_checkpoint() {
                     root: Hash256::zero(),
                 },
                 attestation: Checkpoint {
-                    epoch: Epoch::from(0 as u64),
+                    epoch: Epoch::from(0_u64),
                     root: Hash256::zero(),
                 },
                 is_current: true,
@@ -877,7 +877,7 @@ fn invalid_proposer_slashing_proposal_epoch_mismatch() {
         Err(BlockProcessingError::ProposerSlashingInvalid {
             index: 0,
             reason: ProposerSlashingInvalid::ProposalSlotMismatch(
-                Slot::from(0 as u64),
+                Slot::from(0_u64),
                 Slot::from(128 as u64)
             )
         })