Snowbridge - bump `polkadot-fellows` to 1.4 / 1.5 / 1.6 / 1.7 upcoming-1.6-with-snowbridge subtree

[bkontur]

• prepare PR for fellows - let's see how single PR on polkadot-sdk version update polkadot-fellows/runtimes#101 (comment) - if like Slava did for 1.3 or other way

  • (1.4/1.5) Upgrade to latest polkadot-sdk@1.5 release polkadot-fellows/runtimes#137
  • (1.6) Upgrade to latest polkadot-sdk@1.6 release polkadot-fellows/runtimes#159
  • (1.7) Upgrade to latest polkadot-sdk@1.7 release polkadot-fellows/runtimes#187

• ensure that all PR comments are fixed:

  • Adds Snowbridge to Rococo runtime polkadot-sdk#2522
  • Snowbridge Rococo deployment updates polkadot-sdk#2792

• fix/change all git-ref dependencies like ethapi

  ethabi = { git = "https://github.com/Snowfork/ethabi-decode.git", package = "ethabi-decode", branch = "master", default-features = false }
  

cc: @claravanstaden @vgeddes @alistair-singh

[bkontur]

closing, fellows repo is bumped and Snowbridge is merged in the fellows repo