chore(.github): Add release verification prompts to PR template secti…

…on "Upgrade Considerations" (#10444)

## Description
A topic in last week's kernel meeting was the burden of verifying releases, and even of determining _what_ to verify and _how_ to do so. This is an attempt to make that explicit at a much earlier point in development, with hints regarding future automation potential but no firm commitment of such. Assuming this lands, I expect release instructions to include collecting steps from all constituent PRs and post-release cleanup of any relevant scripts.

### Security Considerations
n/a

### Scaling Considerations
n/a

### Documentation Considerations
n/a

### Testing Considerations
n/a

### Upgrade Considerations
This is intended to increase the maturity of our upgrade process.

.github/PULL_REQUEST_TEMPLATE.md

@@ -32,4 +32,4 @@ refs: #XXXX
 <!-- Every PR should of course come with tests of its own functionality. What additional tests are still needed beyond those unit tests? How does this affect CI, other test automation, or the testnet? -->
 
 ### Upgrade Considerations
-<!-- What aspects of this PR are relevant to upgrading live production systems, and how should they be addressed? -->
+<!-- What aspects of this PR are relevant to upgrading live production systems, and how should they be addressed? What steps should be followed to verify that its changes have been included in a release (ollinet/emerynet/mainnet/etc.) and work successfully there? If the process is elaborate, consider adding a script to scripts/verification/. -->