Add manifest file for Python v3.8.4 x64 (#2496)

Co-authored-by: Nisarg Mehta <mehtanisarg3@gmail.com@users.noreply.github.com>

manifests/Python/Python/3.8.4.yaml

@@ -0,0 +1,19 @@
+Id: Python.Python
+Version: 3.8.4
+Name: Python
+Publisher: Python
+License: PSF LICENSE AGREEMENT FOR PYTHON
+LicenseUrl: https://docs.python.org/3/license.html
+AppMoniker: python
+Tags: python, python3
+Description: Python is a programming language that lets you work more quickly and integrate your systems more effectively.
+Homepage: https://www.python.org
+Installers:
+  - Arch: x64
+    Url: https://www.python.org/ftp/python/3.8.4/python-3.8.4-amd64.exe
+    Sha256: 24CEAD226C8B3DE579E246AA4152BD6C2FF8A613A65998EAC8B66920D9821919
+    InstallerType: exe
+    Switches:
+      Silent: /Quiet
+      SilentWithProgress: /Passive
+      Custom: PrependPath=1