Chore: Upgrade Go to 1.21.3 (#77304)

pkg/services/ngalert/state/historian/encode.go

@@ -3,14 +3,15 @@ package historian
 import (
 	"encoding/json"
 	"fmt"
+	"slices"
 	"strconv"
 	"strings"
 
 	"github.com/gogo/protobuf/proto"
 	"github.com/golang/snappy"
-	"github.com/grafana/grafana/pkg/components/loki/logproto"
 	"github.com/prometheus/common/model"
-	"golang.org/x/exp/slices"
+
+	"github.com/grafana/grafana/pkg/components/loki/logproto"
 )
 
 type JsonEncoder struct{}

pkg/services/ngalert/state/template/funcs.go

@@ -5,10 +5,9 @@ import (
 	"fmt"
 	"net/url"
 	"regexp"
+	"slices"
 	"strings"
 	"text/template"
-
-	"golang.org/x/exp/slices"
 )
 
 type query struct {