ci+docs: support CentOS Stream 9, drop CentOS 8

Refs: #5181
Change-Id: I1d1a0ed02736ef5ec0c28d51f1c4f56f6e00d129
diff --git a/.jenkins.d/40-headers-check.sh b/.jenkins.d/40-headers-check.sh
index 861d8c9..e3493f4 100755
--- a/.jenkins.d/40-headers-check.sh
+++ b/.jenkins.d/40-headers-check.sh
@@ -13,7 +13,7 @@
   exit 0
 fi
 
-if has CentOS-8 $NODE_LABELS; then
+if has CentOS $NODE_LABELS; then
   export PKG_CONFIG_PATH=/usr/local/lib64/pkgconfig
 fi