[build] Add SHA2-SUMS to GHA logs

[bashonly]

In light of what happened with xz's tarballs, I think it would be good to provide a verifiable "chain of custody" from our git repo to our release assets (tarball, binaries).

Our GitHub Actions logs for the build workflow will have a section that looks like this now:

https://github.com/bashonly/yt-dlp/actions/runs/8497175700/job/23275527118

Make SHA2-SUMS files

Run cd ./artifact/
  cd ./artifact/
  sha256sum * | tee ../SHA2-256SUMS
  sha512sum * | tee ../SHA2-512SUMS
  shell: /usr/bin/bash -e {0}
cd1214ccda412c384c0850443dfab2db81e382ee23e6e5fe638a7f2fbd15ee3a  yt-dlp
5d658358b341a90d6c99f56e404b9e4e42f55181d5ed59b5143b75eb98699b92  yt-dlp.exe
8a303ed7e113b1870591d4fc9ddbf7a5d1c8d602c5370914e753cbe81c825a92  yt-dlp.tar.gz
d7484dcc965c308dfaaaa44e2f659ab001f9d65d55112725d34e21df1bc15e93  yt-dlp_linux
28767a12b06e47a523f57c7520c0bf2ef5dde9d301b5bdccb75049a2d2286b09  yt-dlp_linux.zip
6f34dd1638cbf24e8bafd98f2e2c95556d4548199c4aafc444ebf5e4e4905c28  yt-dlp_linux_aarch64
6c14c77988ce494cea2b9b12d9cdc98bb5e526fb6811600c8ae5917fe259f3dc  yt-dlp_linux_armv7l
1aae9f5f8b85d79d33563fe88096676c81ddba8e8766945f4cb42cdb47572f80  yt-dlp_macos
3f83944bae3306b3ff94b6bb83090c1a146f63160c6998e707c2a3ae0a48133f  yt-dlp_macos.zip
7ecfe36e77f4f19f242f8afb39518bdf441ca386be870088bf1f6a11099444e7  yt-dlp_macos_legacy
727b2cf3b4f426f3a9d5cae357eff18f87c21137475d37e0d74b848f875c547f  yt-dlp_min.exe
7aa0582c24f03bc04bbb11b9f3b7faed21618d5715921c86819a0717fdf4bbb0  yt-dlp_win.zip
b048f7fcd9f6b3987616fca6590067e98e9bfcda7a24de336a835b778f81ed43  yt-dlp_x86.exe
1c438729262c7416b313ffd577bcbf867c227aaf27b869c2f2f07f65f3f819b9b931d023b8627dc9039e79e550a0efa0d53a4eb82253752130b53e7bafbcb387  yt-dlp
258ce97c012f70388b906915549db0c31db98e66e83df56ceff3d31eea498c92a2f299f49afb2de8fca4664d4d072e435fe357a3ca2885f4cea00cb40aae7bda  yt-dlp.exe
f757ec9e7767d5aaddf8dc381a0b05659ded3a27c8164ae35ce509959df72f80da9b4d63fba12b6d4346fff7f74c0ec57cbad34c65362cb257d27af42389b080  yt-dlp.tar.gz
272fca3809d1df1c49168727a6c666716a8eb061ed7e171fb33c4226e87759bfe0557cb1c024b94a89f22c9c23a2e18790ce15d9671e9e5bb4c7e9f3c8916d26  yt-dlp_linux
12e37a4ede23f3ca022c961ab7ae65fbd196ce02da7afc1138fbc808c19ee93208e41a6d9df3fbd8a1077f0233a4c78e7ad752fd7ce78723a321f750ff6d048e  yt-dlp_linux.zip
1643f3e553b76413d07c483c84d48a0f2e311b2785d104f79f5f1533b52663ccbb6ecd44a8e2e7657b232391bc99dc2947ad872482136afb0a0bb97d3d10b716  yt-dlp_linux_aarch64
98a6c8c6397965336b7905ac786a455469f6bb1c9152ece7f191dba96b4f969a96e88a068121e4ec3c6acc9dcc0a5696af15962669ab687c26e0589509089a19  yt-dlp_linux_armv7l
136eec8ce6afb64ab1a7887faee9637a9408336cf3f60676422e4159603fd546b6d4698a56374ba268628504cca89f68045034dbfe498cdc6f65cd4b74a1c068  yt-dlp_macos
39de44e968808eeea07417841a15a7bfe58c53d77bfc7a65574d2658eea607c343d9fb2af0237094a244f6884e8dc5bad1216560efbed9ce7d14158eeff8296a  yt-dlp_macos.zip
a485d2904169274ecf07dcdfec4a0963740721952dc6dbc29c9f1a346f38457f0c2b4b7c6a2ded7b19ecb4dce65c262a81198271c33c2dae2765e96fdb529172  yt-dlp_macos_legacy
080e226839223a4be61f81fd325cb6616e45b3a6337e764a671a906a646dfd0e01cedb3e929004c806ee63e09debca774f91490572f28cd353076af70357b467  yt-dlp_min.exe
4ca017bae87b8a519a2b7fced7a6626411b1835d839afe37d21f21233f1f952e180685f7c7571dc0b3db6787609585db57f41c7b5af1243e4e7de93d9fc433db  yt-dlp_win.zip
0e2b0c1294143af9937cac1e20832e1603bc4452a3d777d401cb137501f013d38c443cf79f1e38b2894f74ad865dd5bb077866d80a2de99dd52c0edfab383be0  yt-dlp_x86.exe

Users and downstream packagers can compare the sums in the log with those in the SHA256SUMS and SHA512SUMS release assets to verify that the release assets are indeed the product of our build workflow and have not been tampered with.

Template

Before submitting a pull request make sure you have:

• At least skimmed through contributing guidelines including yt-dlp coding conventions
• Searched the bugtracker for similar pull requests
• Checked the code with flake8 and ran relevant tests

In order to be accepted and merged into yt-dlp each piece of code must be in public domain or released under Unlicense. Check all of the following options that apply:

• I am the original author of this code and I am willing to release it under Unlicense

What is the purpose of your pull request?

• Core bug fix/improvement

[pukkandan]

We used to (intentionally) print it in old workflow. Was accidentally lost during rework

[pukkandan]

Maybe add a comment so the mistake don't happen again