debian/control: minimum version of libtalloc-dev must be >= 2.1.0

Change-Id: Id20871b76c4a5801defb4f534fad635b7f079a13
diff --git a/debian/control b/debian/control
index 05d0c02..771fff2 100644
--- a/debian/control
+++ b/debian/control
@@ -14,7 +14,7 @@
                doxygen,
                libpcsclite-dev,
                pkg-config,
-               libtalloc-dev,
+               libtalloc-dev (>= 2.1.0),
                libsctp-dev,
                libusb-1.0-0-dev,
                libmnl-dev,
@@ -319,7 +319,7 @@
 Multi-Arch: same
 Section: libdevel
 Depends: libosmocore,
-         libtalloc-dev,
+         libtalloc-dev (>= 2.1.0),
          ${misc:Depends}
 Description: Development headers for Open Source MObile COMmunications CORE library
  The header files provided by this package may be used to develop