project: set version

Set the version of the project within the project() declaration so other
cmake scripts can use PROJECT_VERSION.

Signed-off-by: Bill Roberts <bill.roberts@arm.com>
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5585c78..179c3f6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -34,9 +34,15 @@
 cmake_policy(SET CMP0012 NEW)
 
 if(TEST_CPP)
-    project("Mbed TLS" LANGUAGES C CXX)
+    project("Mbed TLS"
+        LANGUAGES C CXX
+        VERSION 3.5.2
+    )
 else()
-    project("Mbed TLS" LANGUAGES C)
+    project("Mbed TLS"
+        LANGUAGES C
+        VERSION 3.5.2
+    )
 endif()
 
 include(GNUInstallDirs)