treewide: Switch to std::format

Reduce our dependence on fmtlib.

Change-Id: I1cc9b372aa366ae26d846470c8ab9d1d52e8db70
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/src/fd/create.cpp b/src/fd/create.cpp
index bfef66f..d9b90f0 100644
--- a/src/fd/create.cpp
+++ b/src/fd/create.cpp
@@ -1,10 +1,11 @@
 #include <fcntl.h>
-#include <fmt/format.h>
 #include <sys/socket.h>
 
 #include <stdplus/fd/create.hpp>
 #include <stdplus/util/cexec.hpp>
 
+#include <format>
+
 namespace stdplus
 {
 namespace fd
@@ -14,7 +15,7 @@
 {
     return DupableFd(
         CHECK_ERRNO(::open(pathname, static_cast<int>(flags), mode),
-                    fmt::format("open `{}`", pathname)));
+                    std::format("open `{}`", pathname)));
 }
 
 DupableFd socket(SocketDomain domain, SocketType type, SocketProto protocol)