Pyinstaller resources.DistributionNotFound 'workalendar'

[LM FP]

Hi!
I have imported workalendar package -together with others packages- to my python script, and It works fine. I compile it with Pyinstaller without errors, but when I run the exe file appears a warning: pkg_resources.DistributionNotFound: The 'workalendar' distribution was not found and is required by the application.

I execute this: C:\Python\Python38\Scripts\pyinstaller.exe --onefile .\main.spec

And when I execute the exe file returns: pkg_resources.DistributionNotFound: The 'workalendar' distribution was not found and is required by the application
[5716] Failed to execute script main


My spec file:

# -*- mode: python ; coding: utf-8 -*-

block_cipher = None


a = Analysis(['main.py'],
         pathex=['C:\\Users\\user\\Downloads\\MyScript',
         'C:\\Python\\Python38\\Lib\\site-packages\\workalendar'],
         binaries=[],
         datas=[],
         hiddenimports=['pkg_resources.py2_warn', 'workalendar-9.0.0.dist-info/*', 'workalendar-9.0.0.dist-info'],
         hookspath=[],
         runtime_hooks=[],
         excludes=[],
         win_no_prefer_redirects=False,
         win_private_assemblies=False,
         cipher=block_cipher,
         noarchive=False)
pyz = PYZ(a.pure, a.zipped_data,
         cipher=block_cipher)
exe = EXE(pyz,
      a.scripts,
      a.binaries,
      a.zipfiles,
      a.datas,
      [],
      name='main',
      debug=False,
      bootloader_ignore_signals=False,
      strip=False,
      upx=True,
      upx_exclude=[],
      runtime_tmpdir=None,
      console=True )

Whats is the problem?