Include fstream

Missing the fstream include is causing build errors, so adding it to fix
the build.

Tested:
Confirmed that it builds.

Change-Id: I3417340256f9965778f7cde0a1d26a33edd2d320
Signed-off-by: Jason M. Bills <jason.m.bills@intel.com>
diff --git a/src/oemcommands.cpp b/src/oemcommands.cpp
index b258e21..5a3cef1 100644
--- a/src/oemcommands.cpp
+++ b/src/oemcommands.cpp
@@ -44,6 +44,7 @@
 
 #include <array>
 #include <filesystem>
+#include <fstream>
 #include <iostream>
 #include <regex>
 #include <set>