CI fails because this style has quite low contrast, which is a bit sad. OTOH, I'm not sure if there's much we can do about that given it's designed by other people and maintained consistent across an array of tools. I see that they increased the contrast for comments at some point, nordtheme/nord#94. Did you incorporate that change? Otherwise, I'm afraid we can't do much more than bypassing this test by editing the min_contrasts.json manually ...

I didn't know about this change they've made. I just updated it to include the nord3 + 10%. If it's still too low contrast, I can increase it further up to 20%.

Also, the file header check fails, you need to do

diff --git a/pygments/styles/nord.py b/pygments/styles/nord.py
index 94c7f23a..15b6d5cb 100644
--- a/pygments/styles/nord.py
+++ b/pygments/styles/nord.py
@@ -1,12 +1,12 @@
 """
     pygments.styles.nord
-    ~~~~~~~~~~~~~~~~~~~~~~~
+    ~~~~~~~~~~~~~~~~~~~~
 
     pygments version of the "nord" theme by Arctic Ice Studio
     https://www.nordtheme.com/
 
-    :copyright: Copyright 2006-2021 by the Pygments team, see AUTHORS.
-    :license: BSD-3 Clause License. See LICENSE for details
+    :copyright: Copyright 2006-2022 by the Pygments team, see AUTHORS.
+    :license: BSD, see LICENSE for details.
 """
 

As they apparently more or less standardized on 10%, I think it's OK to stay with that. This style is not going to be a high-contrast one in any case. That's fine; if you use Pygments just for yourself or for a specific set of people you know, and nobody visually impaired is expected to view the output, a low-contrast style is OK. It's also perfectly OK to provide two versions of the same content, one of which is adapted for low vision. IMHO, we just need to state clearly that the contrast is low, which the style gallery at https://pygments.org/styles/ does.

So I suggest you do:

diff --git a/tests/contrast/min_contrasts.json b/tests/contrast/min_contrasts.json
index ee804304..c8002653 100644
--- a/tests/contrast/min_contrasts.json
+++ b/tests/contrast/min_contrasts.json
@@ -42,5 +42,7 @@
   "gruvbox-light": 3.2,
   "dracula": 1.4,
   "one-dark": 3.7,
-  "lilypond": 2.3
+  "lilypond": 2.3,
+  "nord": 2.4,
+  "nord-darker": 2.8
 }
\ No newline at end of file

Just out of curiosity, what are those numbers in tests/contrast/min_contrasts.json?

It maps style names to min contrast. The contrasts are measured according to the WCAG indicator. The min contrast is just the minimum of the contrasts for each of the tokens in a style.

I got those figures by running python scripts/update_contrasts.py after having commented out the line that tests they're high enough.