The current logic to get the version from the version string depends

on the position (11) which may not work with other postgres variants
because of the different strings they may carry like EnterpriseDB for
an example.

So instead of of using string substring to parse the version, use
string regex match. Also, move up the code to replace the strings
alpha/beta/rc a bit to support the patch

Tested on Linux

CMakeLists.txt

@@ -171,15 +171,16 @@ if(NOT POSTGRESQL_FOUND OR NOT POSTGRESQL_VERSION_STRING)
     message(FATAL_ERROR "PostgreSQL not found - Please check your PostgreSQL installation.")
 endif()
 
+# for XbetaY XalphaY XrcY -> X.Y
+string(REGEX REPLACE "([0-9]+)[beta|alpha|rc|devel].*" "\\1.0" POSTGRESQL_VERSION_STRING ${POSTGRESQL_VERSION_STRING})
 message(STATUS "POSTGRESQL_VERSION_STRING=${POSTGRESQL_VERSION_STRING}")
-string(SUBSTRING "${POSTGRESQL_VERSION_STRING}" 11 -1 POSTGRESQL_VERSION)
 
-# for XbetaY XalphaY XrcY -> X.Y
-string(REGEX REPLACE "^([0-9]+)[beta|alpha|rc|devel].*" "\\1.0" POSTGRESQL_VERSION ${POSTGRESQL_VERSION})
+STRING(REGEX MATCH "([0-9]+)\.([0-9]+)" POSTGRESQL_VERSION "${POSTGRESQL_VERSION_STRING}")
+message(STATUS "POSTGRESQL_VERSION=${POSTGRESQL_VERSION}")
 
 #for X.Y.Z -> XY  Y<10
 string(REGEX REPLACE "^([0-9]+)\\.([0-9]+).*" "\\1\\2" PGSQL_VERSION ${POSTGRESQL_VERSION})
-
+#message(STATUS "PGSQL_VERSION=${PGSQL_VERSION}")
 
 if("${POSTGRESQL_VERSION}" VERSION_LESS "${POSTGRESQL_MINIMUM_VERSION}")
     message(FATAL_ERROR " PostgreSQL ${POSTGRESQL_MINIMUM_VERSION} or greater is required.")