work around link checker being blocked

this is a really annoying failure, but we probably can't do much other
than waiting for IP addresses to switch around or something...

source/conf.py

@@ -427,6 +427,9 @@
     # since linkchecking those URLs will fail before actually deploying them,
     # we ignore them here.
     r"https://nix.dev/manual/.*$",
+    # raspberrypi.com refuses to get hit by the link checker
+    # TODO: remove this when things have cooled down
+    r"https://www.raspberrypi.com/documentation/computers/raspberry-pi.html",
 ]
 
 # Anchors are not present in HTML