[EngAut] TipBot improvements

[mordamax]

Goal

Keep incentivise external contributors to deliver excellent work

There's some tech debt & improvements for this bot

Tasks

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1. Keep Polkadot cache warm #136
   +0
2. Respond with a link to Polkassembly #113
   +0
   
3. Support Testnets #46
   +0
   
4. Run a periodic E2E test targeting new polkadot-sdk releases #145
   +0

[rzadp]

Status update:

• Restored Polkassembly integration after a breaking change in the API: polkassembly descsription isn't updated #132
• Periodically keep Polkadot build cache warm in order to support infrequent PRs: Keep Polkadot cache warm #136

[rzadp]

No updates this week.

[rzadp]

No updates this week.

[rzadp]

Updates:

• Updated the code after a breaking change in a Polkadot release.
  • Updated the integration and E2E tests to run against a most recent v1.7.1 release.
• Proposed a weekly job that will test the code against a most recent Polkadot release, in order to catch errors (like the one above) much earlier, before the release is applied in the runtimes.
• The bot will post a link to Polkassembly in the PR - Comment with a link to Polkassembly referendum #141.
• Support testnets - Added Rococo and Westend testnets.

[rzadp]

One PR is unmerged, but other than that the work is done here.