gstreamer: Disable C5287 warning on MSVC

```
../subprojects/gstreamer/gst/gstpad.c(3866): warning C5287:
operands are different enum types 'GstQueryType' and 'GstQueryTypeFlags';
use an explicit cast to silence this warning
```

We abuse these enums, and MSVC emits a warning for this specific case:

https://learn.microsoft.com/en-us/cpp/error-messages/compiler-warnings/compiler-warnings-c5200-through-c5399

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/9431>

subprojects/gstreamer/gst/gstevent.h

@@ -25,6 +25,10 @@
 #ifndef __GST_EVENT_H__
 #define __GST_EVENT_H__
 
+#ifdef _MSC_VER
+#pragma warning(disable: 5287)
+#endif
+
 typedef struct _GstEvent GstEvent;
 
 /**

subprojects/gstreamer/gst/gstquery.h

@@ -32,6 +32,10 @@
 
 G_BEGIN_DECLS
 
+#ifdef _MSC_VER
+#pragma warning(disable: 5287)
+#endif
+
 typedef struct _GstQuery GstQuery;
 
 #include <gst/gstminiobject.h>

subprojects/gstreamer/gst/gstsegment.h

@@ -27,6 +27,10 @@
 
 G_BEGIN_DECLS
 
+#ifdef _MSC_VER
+#pragma warning(disable: 5287)
+#endif
+
 #define GST_TYPE_SEGMENT             (gst_segment_get_type())
 
 typedef struct _GstSegment GstSegment;