use std::format instead of fmt::format

The std::format is sufficient for the uses in this repository except
for in one file (override_fan_target.cpp, since P2286 isn't supported
by GCC yet).  Switch to std::format whenever possible.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ib2576fb530a4d7ce238e1b0bd95b40b476ec2107
diff --git a/monitor/power_off_rule.hpp b/monitor/power_off_rule.hpp
index 3172bd5..ad17870 100644
--- a/monitor/power_off_rule.hpp
+++ b/monitor/power_off_rule.hpp
@@ -84,7 +84,7 @@
         {
             // Start the action
             getLogger().log(
-                fmt::format("Starting shutdown action '{}' due to cause '{}'",
+                std::format("Starting shutdown action '{}' due to cause '{}'",
                             _action->name(), _cause->name()));
 
             _active = true;
@@ -95,13 +95,13 @@
             // Attempt to cancel the action, but don't force it
             if (_action->cancel(false))
             {
-                getLogger().log(fmt::format("Stopped shutdown action '{}'",
+                getLogger().log(std::format("Stopped shutdown action '{}'",
                                             _action->name()));
                 _active = false;
             }
             else
             {
-                getLogger().log(fmt::format(
+                getLogger().log(std::format(
                     "Could not stop shutdown action '{}'", _action->name()));
             }
         }