Python: drop EOL versions

[adamjstewart]

This PR removes end of life versions of Python from Spack. Specifically, this includes all versions of Python older than 3.7.

See #31824 for rationale. Deprecated in #32615. And #28003.

For anyone using software that relies on Python 2, you have a few options:

• Upgrade the software to support Python 3. The 3to2 tool may get you most of the way there, although more complex libraries may need manual tweaking.
• Add Python 2 as an external package. Many Python libraries do not support Python 2, but you may be able to add older versions that did once upon a time.
• Use Spack 0.19. Spack 0.19 is the last release to officially support Python 3.6 and older
• Create and maintain your own custom repository. Basically, you would need a package for Python 2 and any other Python 2-specific libraries you need.

[adamjstewart]

@spackbot maintainers

[adamjstewart]

Too many packages for the bot, so here's a manual ping. First half:

@AndrewGaspar @BoboTiG @FrankD412 @G-071 @HadrienG2 @HaluskaR @Kerilk @KineticTheory @MakisH @RemiLacroix-IDRIS @Sinan81 @adamjstewart @agoodLANL @ajkotobi @amd-toolchain-support @apdavison @arjun-raj-kuppala @aweits @balay @BarrySmith @bernhardkaindl @boegel @bryanherman @btovar @bvanessen @calebrob6 @cchambreau @charlesg3 @chenwany @chuckatkins @citibeth @cosmicexplorer @danlipsa @demartinofra @dev-zero @dhuth @dorton21 @doutriaux1 @drbenmorgan @dthain @emai-imcs @enrico-usai @eschnett @estebanpauli @estewart08 @francesco-giordano @fsimonis @glennpj @gmarciani @haampie

[adamjstewart]

Second half:

@hanwen-pcluste @jcbowden @jeanbez @jedbrown @jke513 @joseeroman @jppelteret @kwryankrattiger @lee218llnl @leiterrl @likask @liuyangzhuan @luca-heltai @lukeseawalker @marcusboden @matthiasdiener @mhaseeb123 @migueldiascosta @murray55 @mwkrentel @NessieCanCode @pcdslab @pfluegdk @pradyunsg @qobilidop @renjithravindrankannath @rgommers @robertu94 @robqiao @scemama @scheibelp @sethrj @shanedsnyder @skosukhin @smolins @snehring @srekolam @sshudler @svenevs @takluyver @tgaddair @trws @tzanio @v-dobrev @vicentebolea @vvolkl

Can y'all review this PR? It modifies (or in many cases removes) a package for which you are listed as a maintainer.

[migueldiascosta]

regarding the changes to the berkeleygw package, lgtm (I'll separately look into adding back the dependencies using python 3)

[pradyunsg]

Yes please. :)

[srekolam]

reviewed roctracer-dev and looks okay to me.

[rgommers]

Looks like a very good idea. I checked the packages I maintain: py-numpy looks good, py-scipy isn't touched in this PR. Not sure if that was intended; old versions can be dropped there as well.

[tldahlgren]

@scheibelp As investigated during the Spack User meeting, this PR added a conflicts to qt+webkit that precludes building the only version of rstudio in the Spack package.