science/paraview: Fix build after recent upgrade of math/exprtk

FindExprTk.cmake parses the header file exprtk.h to find version,
but the type of this variable changed since exprtk-0.0.2

Reported by:	thierry@

science/paraview/files/patch-VTK_CMake_FindExprTk.cmake

@@ -0,0 +1,15 @@
+- workaround for https://gitlab.kitware.com/paraview/paraview/-/issues/21817
+
+--- VTK/CMake/FindExprTk.cmake.orig	2023-03-11 22:27:31 UTC
++++ VTK/CMake/FindExprTk.cmake
+@@ -21,8 +21,8 @@ mark_as_advanced(ExprTk_INCLUDE_DIR)
+
+ if (ExprTk_INCLUDE_DIR)
+   file(STRINGS "${ExprTk_INCLUDE_DIR}/exprtk.hpp" _exprtk_version_header
+-    REGEX "static const char\\* version")
+-  string(REGEX MATCH "static const char\\* version = \"([0-9.]+)\"" _exprtk_version_match "${_exprtk_version_header}")
++    REGEX "static char_cptr *version")
++  string(REGEX MATCH "static char_cptr *version = \"([0-9.]+)\"" _exprtk_version_match "${_exprtk_version_header}")
+   set(ExprTk_VERSION "${CMAKE_MATCH_1}")
+   unset(_exprtk_version_header)
+   unset(_exprtk_version_match)