tests/docker: fix a win32 error due to portability

docker.py is run during configure, and produces an error: No module
named 'pwd'.

Use a more portable and recommended alternative to lookup the user
"login name".

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20230306122751.2355515-4-marcandre.lureau@redhat.com>

tests/docker/docker.py

@@ -23,10 +23,10 @@
 import tempfile
 import re
 import signal
+import getpass
 from tarfile import TarFile, TarInfo
 from io import StringIO, BytesIO
 from shutil import copy, rmtree
-from pwd import getpwuid
 from datetime import datetime, timedelta
 
 
@@ -316,7 +316,7 @@ def build_image(self, tag, docker_dir, dockerfile,
 
         if user:
             uid = os.getuid()
-            uname = getpwuid(uid).pw_name
+            uname = getpass.getuser()
             tmp_df.write("\n")
             tmp_df.write("RUN id %s 2>/dev/null || useradd -u %d -U %s" %
                          (uname, uid, uname))
@@ -570,7 +570,7 @@ def run(self, args, argv):
 
         if args.user:
             uid = os.getuid()
-            uname = getpwuid(uid).pw_name
+            uname = getpass.getuser()
             df.write("\n")
             df.write("RUN id %s 2>/dev/null || useradd -u %d -U %s" %
                      (uname, uid, uname))