Move to std::format

The OpenBMC project is moving from the fmt project to the built-in
std::format() support.

Update source files and meson files to move to std::format().

Tested:
* Verified builds cleanly in local CI
* Verified all automated tests run successfully
* Verified builds cleanly in bitbake
* Verified an affected phosphor-psu-monitor journal message still works
  correctly.
* Verified an affected phosphor-power-sequencer journal message still
  works correctly.

Change-Id: I97b63cf9d132e2b6f173afb30953a9083d68133f
Signed-off-by: Shawn McCarney <shawnmm@us.ibm.com>
diff --git a/phosphor-power-supply/util.cpp b/phosphor-power-supply/util.cpp
index 503e1c3..d1253da 100644
--- a/phosphor-power-supply/util.cpp
+++ b/phosphor-power-supply/util.cpp
@@ -62,7 +62,7 @@
         catch (const std::exception& e)
         {
             log<level::ERR>(
-                fmt::format("Failed to get_value of GPIO line: {}", e.what())
+                std::format("Failed to get_value of GPIO line: {}", e.what())
                     .c_str());
             line.release();
             throw;