Use Botan 3.1.1 for tests

The all-zero Ed25519 public key is rejected by botan_pubkey_check_key()
when the key is loaded.

Note that Botan 3 requires GCC 11 or CLANG 14, i.e. can't easily be built
on Debian bullseye or Ubuntu 20.04.

The thread-local storage function gets flagged via various botan FFI
functions when using Botan 3, whitelist that instead of all of them.

testing/scripts/recipes/011_botan.mk

@@ -2,7 +2,7 @@
 
 PKG = botan
 SRC = https://github.com/randombit/$(PKG).git
-REV = 2.19.3
+REV = 3.1.1
 
 NUM_CPUS := $(shell getconf _NPROCESSORS_ONLN)