Upgrade to polkadot-v1.6.0 (!229)

* check live tests

* cargo check benchmarks after rebase

* cargo check tests after rebase

* update metadata after rebase

* cargo check after rebase

* cargo fmt after rebase

* upgrade runtime to polkadot v1.6.0

upgrade node to polkadot v1.6.0

upgrade distance oracle to polkadot v1.6.0

upgrade end2end tests

upgrade xtask to polkadot v1.6.0

update repository paths to duniter polkadot v1.6.0

fix #131

optimize end2end test

fix review errors

update subxt branch

update test comment