Poll nitter instances only in nightly build

From the recent changes to twitter/X, it sounds like guest accounts are
now required for nitter, which are more easily rate limited. To avoid
any impact from Farside, the instances are now health checked in the
nightly build using https://status.d420.de (this doesn't seem to be
directly associated with the nitter maintainers, so might not be
entirely future-proof).

.github/workflows/update-instances.yml

@@ -109,6 +109,23 @@ jobs:
 
         apply_update
 
+        # ==============================================================
+        # Nitter update
+        # ==============================================================
+        curl -s https://status.d420.de/api/v1/instances | \
+          jq '[
+            .hosts |
+            to_entries[] |
+            select(.value.healthy == true) |
+            .value.url ] |
+            sort' > nitter-tmp.json
+
+        jq --slurpfile nitter nitter-tmp.json \
+          '( .[] | select(.type == "nitter") )
+          .instances |= $nitter[0]' services-full.json > services.tmp.json
+
+        apply_update
+
         # ==============================================================
         # SimplyTranslate update
         # ==============================================================

lib/farside/instances.ex

@@ -7,9 +7,9 @@ defmodule Farside.Instances do
   @debug_header "======== "
   @debug_spacer "         "
 
-  # SearXNG instance uptimes are inspected as part of the nightly Farside build,
+  # These instance uptimes are inspected as part of the nightly Farside build,
   # and should not be included in the constant periodic update.
-  @skip_service_updates ["searxng"]
+  @skip_service_updates ["searxng", "nitter"]
 
   def sync() do
     File.rename(@update_file, "#{@update_file}-prev")