Added Pinned pkgs info

[EaglePPP]

e.g:
pywin32==306 is available (you have 304) [Pinned]
tornado==6.3.2 is available (you have 6.1)

Tested only on Windows

[jgonggrijp]

Great suggestion, thanks!

I want to merge this, but I have three requests:

• Please add a test so that the feature can be verified in CI. I think this feature is doable with the existing cram test setup.
• Please use the word "constrained" instead of "pinned". This makes it less ambiguous with "pinned dependencies" in a requirements.txt.
• Please make it clear in the output which version is listed in the constraints file. If it is guaranteed to be equal to the installed version, I suggest pywin32==306 is available (you have 304, constrained). Otherwise, I suggest pywin32==306 is available (you have 304) [Constrained to 304].