Unsuppress annotation_highlight_opacity.pdf for Windows GDI

This test is currently passing. It should have been unsuppressed as part
of https://pdfium-review.googlesource.com/112352.

Change-Id: Ib9e9d6a43ed8df0534d46e2e80cd5feeae7d020c
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/112852
Reviewed-by: Nigi <nigi@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
diff --git a/testing/SUPPRESSIONS b/testing/SUPPRESSIONS
index 14e1135..2f469b1 100644
--- a/testing/SUPPRESSIONS
+++ b/testing/SUPPRESSIONS
@@ -568,7 +568,6 @@
 FRC_8_8.2.4_View_D.pdf * * * gdi
 FRC_9_8.2.4_View_T.pdf * * * gdi
 annotation_circle_fill_opacity.pdf * * * gdi
-annotation_highlight_opacity.pdf * * * gdi
 annotation_square_fill_opacity.pdf * * * gdi
 annotation_square_fill_opacity_dash.pdf * * * gdi
 bug_0_length_line.pdf * * * gdi