refactor: replace golang.org/x/exp/slices with slices (#16772)

The experimental functions in `golang.org/x/exp/slices` are now
available in the standard library since Go 1.21.

Reference: https://go.dev/doc/go1.21#slices

Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>

coderd/agentapi/lifecycle.go

@@ -3,10 +3,10 @@ package agentapi
 import (
 	"context"
 	"database/sql"
+	"slices"
 	"time"
 
 	"github.com/google/uuid"
-	"golang.org/x/exp/slices"
 	"golang.org/x/mod/semver"
 	"golang.org/x/xerrors"
 	"google.golang.org/protobuf/types/known/timestamppb"