utils.cpp: Remove duplicately defined function

this was an ODR violation: the same function was defined twice, once
with `inline` specifier in utils.h, and once without `inline` in
utils.cpp

it happened to work on clang and gcc and msvc, most of the time, but
broke in the conda build on Windows

Signed-off-by: Tom Jakubowski <tom@prospective.dev>

cpp/perspective/src/cpp/utils.cpp

@@ -125,12 +125,6 @@ parse_all_date_time(
     );
 }
 
-bool
-parse_all_date_time(std::tm& tm, std::string_view date_time_str) {
-    std::chrono::system_clock::time_point tp;
-    return parse_all_date_time(tm, tp, date_time_str);
-}
-
 bool
 parse_all_date_time(
     std::chrono::system_clock::time_point& tp, std::string_view date_time_str