Merge branch 'coq_19059' into 'master'

Prepare for https://github.com/coq/coq/pull/19059

See merge request iris/stdpp!554

Makefile.coq.local

@@ -27,7 +27,7 @@ COQ_TEST=$(COQTOP) $(COQDEBUG) -batch -test-mode
 # These versions of Coq are known to have different output so we don't test them.
 # Need to make this a lazy variable (`=` instead of `:=`) since COQ_VERSION is only set later.
 # Make sure to recognize both 8.$NUM.0 and 8.$NUM+alpha.
-COQ_NOREF=$(shell echo "$(COQ_VERSION)" | grep -E "^8\.(16|17|18|20)[.+]" -q && echo 1)
+COQ_NOREF=$(shell echo "$(COQ_VERSION)" | grep -E "^8\.(16|17|18|20|21)[.+]" -q && echo 1)
 
 tests/.coqdeps.d: $(TESTFILES)
 	$(SHOW)'COQDEP TESTFILES'