[WIP] Add Linux support

[jkirk]

scripts/linux/build is a modified version of scripts/windows/build.bat.

It just takes the modified ./scripts/linux/update-version-info.py + the unmodified ./scripts/windows/git-xl-version-info.py files and uses them to build the binary via pyinstaller.

I also updated pytinstaller to fix the following problem:

      ❯ pip install -r requirements.txt
      Collecting colorama==0.3.9
        Using cached colorama-0.3.9-py2.py3-none-any.whl (20 kB)
      Collecting oletools==0.60
        Using cached oletools-0.60-py2.py3-none-any.whl (968 kB)
      ERROR: Ignored the following versions that require a different python version: 4.10 Requires-Python <3.11,>=3.6; 4.6 Requires-Python <3.11,>=3.6; 4.7 Requires-Python <3.11,>=3.6; 4.8 Requires-Python <3.11,>=3.6; 4.9 Requires-Python <3.11,>=3.6; 5.0 Requires-Python <3.11,>=3.7; 5.0.1 Requires-Python <3.11,>=3.7; 5.1 Requires-Python <3.11,>=3.7; 5.2 Requires-Python <3.11,>=3.7; 5.3 Requires-Python <3.11,>=3.7; 5.4 Requires-Python <3.11,>=3.7; 5.4.1 Requires-Python <3.11,>=3.7
      ERROR: Could not find a version that satisfies the requirement pyinstaller==4.10 (from versions: 2.0, 2.1, 3.0, 3.1, 3.1.1, 3.2, 3.2.1, 3.3, 3.3.1, 3.4, 3.5, 3.6, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.5.1, 5.5, 5.6, 5.6.1, 5.6.2, 5.7.0, 5.8.0, 5.9.0, 5.10.0, 5.10.1, 5.11.0, 5.12.0, 5.13.0, 5.13.1, 5.13.2, 6.0.0, 6.1.0, 6.2.0, 6.3.0)
      ERROR: No matching distribution found for pyinstaller==4.10

It builds:

❯ scripts/linux/build                 
-----------                                                         
Version tag: 0.0.0                                                                                                                      
Build number: 0                                                                                                                         
Commit hash: dev                                                                                                                        
Generate file version: 0.0.0.0                                      
-----------                                                         
81 INFO: PyInstaller: 6.3.0                                                                                                             
81 INFO: Python: 3.11.2                                                                                                                 
82 INFO: Platform: Linux-6.1.0-17-amd64-x86_64-with-glibc2.36                                                                           
82 INFO: wrote /home/jkirk/projects/python-dev/git-xl/git-xl-diff-x64.spec                                                              
83 INFO: Extending PYTHONPATH with paths                            
['/home/jkirk/projects/python-dev/git-xl/src'] 
[...]
2598 INFO: checking PKG
2598 INFO: Building because toc changed
2598 INFO: Building PKG (CArchive) git-xl-x64.pkg
4750 INFO: Building PKG (CArchive) git-xl-x64.pkg completed successfully.
4750 INFO: Bootloader /home/jkirk/projects/python-dev/git-xl/venv3/lib/python3.11/site-packages/PyInstaller/bootloader/Linux-64bit-intel/run
4750 INFO: checking EXE
4751 INFO: Building because toc changed
4751 INFO: Building EXE from EXE-00.toc
4751 INFO: Copying bootloader EXE to /home/jkirk/projects/python-dev/git-xl/dist/git-xl-x64
4752 INFO: Appending PKG archive to custom ELF section in EXE
4763 INFO: Building EXE from EXE-00.toc completed successfully.
scripts/linux/build  13,22s user 0,57s system 98% cpu 13,928 total

And ./git-xl-x64 runs:

 ❯ ./git-xl-x64 --help
git-xl/0.0.0 (windows; Python 3.11.2); git dev
git xl <command> [<args>]

Git xl is a system for managing Excel workbook files in
association with a Git repository. Git xl:
* installs a special git-diff for Excel workbook files 
* makes Git ignore temporary Excel files via .gitignore

Commands
--------

* git xl env:
    Display the Git xl environment.
* git xl version:
    Report the version number.
* git xl install:
    Install Git xl.
* git xl uninstall:
    Uninstall Git xl.

But there are still things to do, to make it work and close #39. Until then, I mark this as [WIP].