unconditionally use int64 for times (#7692)

* unconditionally use int64 for times

* import inSeconds

Author: tersec

beacon_chain/beacon_clock.nim

@@ -13,7 +13,8 @@ import
   chronos/timer, chronicles,
   ./spec/beacon_time
 
-from std/times import Time, getTime, fromUnix, toUnix, `<`, `-`, inNanoseconds
+from std/times import
+  Time, getTime, fromUnix, toUnix, `<`, `-`, inNanoseconds, inSeconds
 
 export timer.Duration, Moment, now, beacon_time
 
@@ -55,12 +56,12 @@ proc init*(
       unixGenesis = fromUnix(genesis_time.int64)
       # GENESIS_SLOT offsets slot time, but to simplify calculations, we apply
       # that offset to genesis instead of applying it at every time conversion
-      unixGenesisOffset = times.seconds(
+      unixGenesisOffset = fromUnix(
         (GENESIS_SLOT.int64 * timeParams.SLOT_DURATION).seconds)
 
     Opt.some T(
       timeParams: timeParams,
-      genesis: unixGenesis - unixGenesisOffset)
+      genesis: (unixGenesis - unixGenesisOffset).inSeconds.fromUnix)
 
 func timeParams*(c: BeaconClock): TimeParams =
   c.timeParams  # Readonly