DOC: Use the needle.jpg image hosted on GitHub for stability (#4674)

Author: seisman

examples/gallery/images/image.py

@@ -22,7 +22,7 @@
 # the current plot, scale it to a width of 8 centimeters and draw a rectangular border
 # around it.
 fig.image(
-    imagefile="https://oceania.generic-mapping-tools.org/cache/needle.jpg",
+    imagefile="https://github.com/GenericMappingTools/gmtserver-admin/raw/master/cache/needle.jpg",
     position=Position((1, 1), cstype="mapcoords", anchor="MC"),
     width="8c",
     box=True,