Add hooks for zoneinfo and backports.zoneinfo

On Windows, these packages use timezone data from the tzdata
package. Due to lack of direct import (the data is loaded using
importlib.resources), we need to add a hiddenimport. On other OSes,
system-wide timezone data is used by default.

news/339.new.1.rst

@@ -0,0 +1 @@
+Add hooks for ``zoneinfo`` and ``backports.zoneinfo``.

requirements-test-libraries.txt

@@ -6,6 +6,7 @@ importlib_resources==5.3.0; python_version < '3.9'
 av==8.0.3
 adbutils==0.11.0; sys_platform == 'darwin' or sys_platform == 'win32'
 APScheduler==3.8.0
+backports.zoneinfo==0.2.1; python_version < '3.9'
 boto==2.49.0
 boto3==1.18.63
 botocore==1.21.63

src/_pyinstaller_hooks_contrib/hooks/stdhooks/hook-backports.zoneinfo.py

@@ -0,0 +1,18 @@
+# ------------------------------------------------------------------
+# Copyright (c) 2021 PyInstaller Development Team.
+#
+# This file is distributed under the terms of the GNU General Public
+# License (version 2.0 or later).
+#
+# The full license is available in LICENSE.GPL.txt, distributed with
+# this software.
+#
+# SPDX-License-Identifier: GPL-2.0-or-later
+# ------------------------------------------------------------------
+
+from PyInstaller.compat import is_win
+
+# On Windows, timezone data is provided by the tzdata package that is
+# not directly loaded.
+if is_win:
+    hiddenimports = ['tzdata']

src/_pyinstaller_hooks_contrib/hooks/stdhooks/hook-zoneinfo.py

@@ -0,0 +1,18 @@
+# ------------------------------------------------------------------
+# Copyright (c) 2021 PyInstaller Development Team.
+#
+# This file is distributed under the terms of the GNU General Public
+# License (version 2.0 or later).
+#
+# The full license is available in LICENSE.GPL.txt, distributed with
+# this software.
+#
+# SPDX-License-Identifier: GPL-2.0-or-later
+# ------------------------------------------------------------------
+
+from PyInstaller.compat import is_win
+
+# On Windows, timezone data is provided by the tzdata package that is
+# not directly loaded.
+if is_win:
+    hiddenimports = ['tzdata']

src/_pyinstaller_hooks_contrib/tests/test_libraries.py

@@ -913,3 +913,25 @@ def test_tzdata(pyi_builder):
 
         print(data)
         """)
+
+
+@importorskip("backports.zoneinfo")
+@pytest.mark.skipif(is_win and not can_import_module('tzdata'),
+                    reason='On Windows, backports.zoneinfo requires tzdata.')
+def test_backports_zoneinfo(pyi_builder):
+    pyi_builder.test_source("""
+        from backports import zoneinfo
+        tz = zoneinfo.ZoneInfo("Europe/Ljubljana")
+        print(tz)
+        """)
+
+
+@importorskip("zoneinfo")
+@pytest.mark.skipif(is_win and not can_import_module('tzdata'),
+                    reason='On Windows, zoneinfo requires tzdata.')
+def test_zoneinfo(pyi_builder):
+    pyi_builder.test_source("""
+        import zoneinfo
+        tz = zoneinfo.ZoneInfo("Europe/Ljubljana")
+        print(tz)
+        """)