Add sha256 checksums file to release

[hnrkndrssn]

Example file that will be added to GitHub release:

f6d8f6d2b9c09b8b0cba3047f53c9f6a1655414a4682d48ddc1773659ad1cfb7 carnac-2.1.114-full.nupkg
0a42a54c1f3b0d139d2abee8b4935371141541d4bcf80033836d7e6805b5f48e carnac-2.1.117-delta.nupkg
0385ea9f87cd53774debffa166748f6ca58380c69520e71e4d33291751a50a4b carnac-2.1.117-full.nupkg
9a3b317b05b87b03396b7dffe20fd6b2ccafe4abc066d873b8f2d629ac0f56e7 carnac-2.1.141-delta.nupkg
8babc978a86ec578755d860116356f774c56bd91719b4fe5ed3dbf8caa3be06b carnac-2.1.141-full.nupkg
d598fd3bcef62f69fa8e4c535ca2985caefe64bb1c6e85b7d69ee301dc851db8 carnac-2.1.142-delta.nupkg
ec9fc41fe1f3b81a0a37238954e52c9fc2462a9fd98047ec20743eddf3dd7025 carnac-2.1.142-full.nupkg
de742b0d4fe73a63143f368cfc0e376ef2e903ae98ac9943d7d1ffcb6caebe7a carnac-2.2.155-delta.nupkg
8e065d2bfeffe899be8df4581f63077ccad593bf7024a7651836e9a93283886b carnac-2.2.155-full.nupkg
cd752444fda69f7e57a54a420fac713711816d98fef3e6050578ea3495fbc7e5 carnac-2.2.169-delta.nupkg
4881b4a48b1a13ca422c38821b2fa9929c0bf1783e486cb478e7dfab9fec3456 carnac-2.2.169-full.nupkg
126f3ac18ede3bfb48d7a03094f15cb8dbd5c29fd89d8c975b24d4baad57f0be RELEASES
7da0fa3fb30647fa98f6a0647376b156b382ee9804689d7e56ad7de7111a9940 Setup.exe
ea340dd8c7d552a0a1705dc81d85cec9d0220181a932c0932fa0e0ddcef57e52 carnac.2.2.169.zip

Fixes #203

[hnrkndrssn]

Thanks @shiftkey, I was thinking if I should ping you the other day to see if you wanted to cast your 👀 over my PRs...seems the invisible 🦇 📡 went through anyway 😁