meson: fix -werror, tests and format

Dependent projects are compiled with -werror and failing because of this
dependency.

For example phosphor-bmc-code-mgmt.

```
../subprojects/stdplus/include/stdplus/net/addr/ip.hpp:550:26: error: space between quotes and suffix is deprecated in C++23 [-Werror=deprecated-literal-operator]
  550 | constexpr auto operator"" _ip() noexcept
      |                          ^~
      |                          --
```

test/io_uring.cpp had to be fixed because there was an access to an
optional which had been ```.reset()``` previously.

Tested: Unit Tests Pass

Change-Id: Iae8bff96cf69a82aea8c1964cfd35908946d7f47
Signed-off-by: Alexander Hansen <alexander.hansen@9elements.com>
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
diff --git a/test/fd/fmt.cpp b/test/fd/fmt.cpp
index bdac7a4..cf4a319 100644
--- a/test/fd/fmt.cpp
+++ b/test/fd/fmt.cpp
@@ -27,7 +27,7 @@
         buf.flush();
 
         EXPECT_EQ(6, fd.lseek(0, Whence::Cur));
-        buf.append(FMT_COMPILE("{}"), std::string(2050, 'a'));
+        buf.append("{}", std::string(2050, 'a'));
         EXPECT_EQ(6, fd.lseek(0, Whence::Cur));
         buf.append("{}", std::string(2050, 'a'));
         EXPECT_EQ(4106, fd.lseek(0, Whence::Cur));