bpo-43651: Fix test_compileall with PEP 597 (GH-25128)

diff --git a/Lib/compileall.py b/Lib/compileall.py
index 672cb43..61b4c5c 100644
--- a/Lib/compileall.py
+++ b/Lib/compileall.py
@@ -407,7 +407,8 @@ def main():
     # if flist is provided then load it
     if args.flist:
         try:
-            with (sys.stdin if args.flist=='-' else open(args.flist)) as f:
+            with (sys.stdin if args.flist=='-' else
+                    open(args.flist, encoding="utf-8")) as f:
                 for line in f:
                     compile_dests.append(line.strip())
         except OSError: