configure.ac: Depend on talloc 2.1.0

With recent commit (see below) libosmocore started using talloc API
talloc_pooled_object(), which is available only startinf from talloc
2.1.0.
Let's bump required version check in configure.ac accordingly.

Fixes: b72867f0e68c96ca25e1f9929ce92be0a802db6b
Change-Id: Id9d10d02b9b4500a246fcc3e071a14c1d7da4f14
diff --git a/configure.ac b/configure.ac
index f5af0d0..b36bd6f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -150,7 +150,7 @@
 dnl Generate the output
 AC_CONFIG_HEADER(config.h)
 
-PKG_CHECK_MODULES(TALLOC, [talloc >= 2.0.1])
+PKG_CHECK_MODULES(TALLOC, [talloc >= 2.1.0])
 
 AC_ARG_ENABLE([pcsc], [AS_HELP_STRING([--disable-pcsc], [Build without PC/SC support])],
     [