module test of clang-19 looks good, adding to supported

Author: JeffGarland

CMakeLists.txt

@@ -12,7 +12,7 @@ project(
 # gersemi: off
 
 # Modules opt in only on compilers that support g++-15 and clang-20
-if (CMAKE_CXX_COMPILER_ID STREQUAL "Clang" AND CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL 20)
+if (CMAKE_CXX_COMPILER_ID STREQUAL "Clang" AND CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL 19)
     set(CMAKE_CXX_SCAN_FOR_MODULES 1)
 elseif (CMAKE_CXX_COMPILER_ID STREQUAL "GNU" AND CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL 15)
     set(CMAKE_CXX_SCAN_FOR_MODULES 1)