Parse datetimes in UTC

parser.go

diff --git a/parser.go b/parser.go
index 8911261..e550967 100644
--- a/parser.go
+++ b/parser.go
@@ -236,7 +236,7 @@
 		}
 		return val
 	case tokenDate:
-		val, err := time.Parse(time.RFC3339Nano, tok.val)
+		val, err := time.ParseInLocation(time.RFC3339Nano, tok.val, time.UTC)
 		if err != nil {
 			p.raiseError(tok, "%s", err)
 		}

parser_test.go

diff --git a/parser_test.go b/parser_test.go
index 8d55ccd..2998913 100644
--- a/parser_test.go
+++ b/parser_test.go
@@ -87,18 +87,16 @@
 }
 
 func TestDateOffset(t *testing.T) {
-	target, _ := time.Parse(time.RFC3339Nano, "1979-05-27T00:32:00-07:00")
 	tree, err := Load("a = 1979-05-27T00:32:00-07:00")
 	assertTree(t, tree, err, map[string]interface{}{
-		"a": target,
+		"a": time.Date(1979, time.May, 27, 0, 32, 0, 0, time.FixedZone("", -7*60*60)),
 	})
 }
 
 func TestDateNano(t *testing.T) {
-	target, _ := time.Parse(time.RFC3339Nano, "1979-05-27T00:32:00.999999999-07:00")
 	tree, err := Load("a = 1979-05-27T00:32:00.999999999-07:00")
 	assertTree(t, tree, err, map[string]interface{}{
-		"a": target,
+		"a": time.Date(1979, time.May, 27, 0, 32, 0, 999999999, time.FixedZone("", -7*60*60)),
 	})
 }