build: require gcc >= 9.1, recommend gcc >= 10.2

Similarly, recommend clang 10 or later. On macOS, the minimum Xcode
version is now 11, the recommended one is still 13 or later.

Change-Id: Ie83d662f7b1a1bfe95d51a823e5d87ad1c49d81c
diff --git a/.jenkins.d/00-deps.sh b/.jenkins.d/00-deps.sh
index c20d217..bac6927 100755
--- a/.jenkins.d/00-deps.sh
+++ b/.jenkins.d/00-deps.sh
@@ -19,7 +19,7 @@
     pkg-config
     python3
 )
-FORMULAE=(boost openssl pkg-config)
+FORMULAE=(boost openssl pkgconf)
 PIP_PKGS=()
 case $JOB_NAME in
     *code-coverage)