Fix error converting to double char8_t

Author: orefkov

include/simstr/sstring.h

@@ -306,7 +306,7 @@ class str_algs : public str_src_algs<K, StrRef, Impl, Mutable> {
         #ifdef __linux__
         if constexpr(sizeof(K) == 1) {
             double d{};
-            if (std::from_chars(ptr, ptr + len, d).ec == std::errc{}) {
+            if (std::from_chars((const u8s*)ptr, (const u8s*)ptr + len, d).ec == std::errc{}) {
                 return d;
             }
             return {};

tests/test_str.cpp

@@ -484,6 +484,8 @@ TEST(SimStr, ToInt) {
 TEST(SimStr, to_double) {
     EXPECT_EQ(ssa{"  123"}.to_double(), 123.0);
     EXPECT_EQ(ssa{"  123.1"}.to_double(), 123.1);
+    EXPECT_EQ(ssb{u8"  123"}.to_double(), 123.0);
+    EXPECT_EQ(ssb{u8"  123.1"}.to_double(), 123.1);
     EXPECT_EQ(ssu{u"  123.13434"}.to_double(), 123.13434);
     EXPECT_EQ(ssuu{U"  123.13434"}.to_double(), 123.13434);
     EXPECT_EQ(ssw{L"  123.13434"}.to_double(), 123.13434);