Just use c++17

Not worth

meson.build

@@ -1,6 +1,6 @@
 project('shapefile-test', 'cpp',
     default_options : [
-        'cpp_std=c++20',
+        'cpp_std=c++17',
         'warning_level=3',
         'buildtype=release',
     ]

src/main.cpp

@@ -162,9 +162,9 @@ int main(int argc, char *argv[]) {
 		}
 
 		all_fires.push_back(month_info{
-			.n_fires = n_fires_month,
-			.name = MONTH,
-			.days = std::move(all_days),
+			n_fires_month,
+			MONTH,
+			std::move(all_days),
 		});
 	}