Use actual C-Blosc2 2.0.0.rc.1 sources

FrancescAlted · FrancescAlted · commit 801922fb1ee0 · 2021-05-14T20:45:18.000+02:00
diff --git a/blosc2/c-blosc2 b/blosc2/c-blosc2
@@ -1 +1 @@
-Subproject commit 4180246f87b6058a14931c1d79ddd8b97c290bdc
+Subproject commit 5b8fe5ab3de82d2572b8065f563e19639b02a5e1
