Use two different find_package() calls

CMakeLists.txt

@@ -278,15 +278,13 @@ if(openPMD_USE_INTERNAL_TOML11)
     add_subdirectory("${openPMD_SOURCE_DIR}/share/openPMD/thirdParty/toml11")
     message(STATUS "toml11: Using INTERNAL version '3.7.1'")
 else()
-    find_package(toml11 CONFIG REQUIRED)
-    # Need to check the version manually. toml11 4.0 was a breaking change, so
-    # find_package(toml11 3.7.1) would not accept versions 4.0+.
-    # We support both 3.* and 4.*.
-    if(${toml11_VERSION} VERSION_LESS 3.7.1)
-        message(FATAL_ERROR "toml11: Found version '${toml11_VERSION}', but requires version '3.7.1' at least.")
-    else()
-        message(STATUS "toml11: Found version '${toml11_VERSION}'")
+    # Since toml11 4.0 was a breaking change,
+    # it needs separate find_package() calls
+    find_package(toml11 3.7.0 CONFIG QUIET)
+    if(NOT toml11_FOUND)
+        find_package(toml11 4.0 CONFIG REQUIRED)
     endif()
+    message(STATUS "toml11: Found version '${toml11_VERSION}'")
 endif()
 add_library(openPMD::thirdparty::toml11 INTERFACE IMPORTED)
 target_link_libraries(openPMD::thirdparty::toml11