Bump version to 4.0.0

Signed-off-by: David Horstmann <david.horstmann@arm.com>
diff --git a/CMakeLists.txt b/CMakeLists.txt
index df4bf6b..b1af566 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -40,12 +40,12 @@
 if(TEST_CPP)
     project("Mbed TLS"
         LANGUAGES C CXX
-        VERSION 3.6.0
+        VERSION 4.0.0
     )
 else()
     project("Mbed TLS"
         LANGUAGES C
-        VERSION 3.6.0
+        VERSION 4.0.0
     )
 endif()
 
@@ -458,7 +458,7 @@
     write_basic_package_version_file(
         "cmake/MbedTLSConfigVersion.cmake"
             COMPATIBILITY SameMajorVersion
-            VERSION 3.6.0)
+            VERSION 4.0.0)
 
     install(
         FILES "${CMAKE_CURRENT_BINARY_DIR}/cmake/MbedTLSConfig.cmake"