Update for macos Qt version

- Update package.py to include a pyinstaller based packaging
- Update requirements and requirements-extra
- Add icon for macos
- Add macos.md for instructions

macos.md

@@ -0,0 +1,53 @@
+## How to build dupeGuru for macos
+
+### Prerequisites
+
+- [Python 3.6+][python]
+- [Xcode 12.3][xcode] or just Xcode command line tools (older versions can be used if not interested in arm macs)
+- [Homebrew][homebrew]
+- [qt5](https://www.qt.io/)
+
+#### Prerequisite setup
+1. Install Xcode if desired
+2. Install [Homebrew][homebrew], if not on the path after install (arm based Macs) create `~/.zshrc` 
+with `export PATH="/opt/homebrew/bin:$PATH"`. Will need to reload terminal or source the file to take 
+affect.
+3. Install qt5 with `brew`. If you are using a version of macos without system python 3.6+ then you will 
+also need to install that via brew or with pyenv.
+
+        $ brew install qt5
+
+    NOTE: Using `brew` to install qt5 is to allow pyqt5 to build without a native wheel
+    available.  If you are using an intel based mac you can probably skip this step.
+
+4. May need to launch a new terminal to have everything working.
+
+### With build.py
+OSX comes with a version of python 3 by default in newer versions of OSX.  To produce universal 
+builds either the 3.8 version shipped in macos or 3.9.1 or newer needs to be used. If needing to
+build pyqt5 from source then the first line below is needed, else it may be omitted. (Path shown is 
+for an arm mac.)
+
+    $ export PATH="/opt/homebrew/opt/qt/bin:$PATH"
+    $ cd <dupeGuru directory>
+    $ python3 -m venv ./env
+    $ source ./env/bin/activate
+    $ pip install -r requirements.txt
+    $ python build.py
+    $ python run.py
+
+### Generate OSX Packages
+The extra requirements need to be installed to run packaging: `pip install -r requirements-extra.txt`. 
+Run the following in the respective virtual environment.
+
+    $ python package.py
+
+This will produce a dupeGuru.app in the dist folder.
+
+### Running tests
+The complete test suite can be run with tox just like on linux. NOTE: The extra requirements need to 
+be installed to run unit tests: `pip install -r requirements-extra.txt`.
+
+[python]: http://www.python.org/
+[homebrew]: https://brew.sh/
+[xcode]: https://developer.apple.com/xcode/