[ox/std] Fix some type implicit conversions in ox_itoa

(synced from f514b33b06)

src/ox/std/strops.hpp

@@ -170,7 +170,7 @@ constexpr T ox_itoa(Integer v, T str) noexcept {
 		constexpr auto base = 10;
 		auto it = 0;
 		if (val < 0) {
-			str[it] = '-';
+			str[static_cast<std::size_t>(it)] = '-';
 			it++;
 		}
 		while (mod) {
@@ -183,11 +183,11 @@ constexpr T ox_itoa(Integer v, T str) noexcept {
 					start = 'a';
 					digit -= 10;
 				}
-				str[it] = static_cast<typename ox::remove_reference<decltype(str[0])>::type>(start + digit);
+				str[static_cast<std::size_t>(it)] = static_cast<typename ox::remove_reference<decltype(str[0])>::type>(start + digit);
 				it++;
 			}
 		}
-		str[it] = 0;
+		str[static_cast<std::size_t>(it)] = 0;
 	} else {
 		// 0 is a special case
 		str[0] = '0';