internal/telemetry: update test for valid version with GOEXPERIMENT

Add a test case for GOEXPERIMENT toolchain versions after CL 719701.

For golang/go#75953.

Change-Id: Ic134141d54649e053efa17ed05f2f9292c2735f9
Reviewed-on: https://go-review.googlesource.com/c/telemetry/+/720303
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Michael Matloob <matloob@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Michael Matloob <matloob@google.com>

internal/telemetry/proginfo_test.go

diff --git a/internal/telemetry/proginfo_test.go b/internal/telemetry/proginfo_test.go
index 4946ace..ccefb1a 100644
--- a/internal/telemetry/proginfo_test.go
+++ b/internal/telemetry/proginfo_test.go
@@ -84,6 +84,10 @@
 			"go1.23.0",
 		},
 		{
+			"go1.26rc1",
+			"go1.26rc1",
+		},
+		{
 			"go1.25-devel_9ce47e66e8 Wed Mar 26 03:48:50 2025 -0700",
 			"devel",
 		},
@@ -92,6 +96,10 @@
 			"devel",
 		},
 		{
+			"go1.26rc1-X:nodwarf5",
+			"devel",
+		},
+		{
 			"go1.23rc2 X:aliastypeparams",
 			"devel",
 		},