release.yml: to eliminate manual editing of app.go

[AskAlexSharov]

now to release v3.4.0-rc.1 i need:

• create manual PR to change Modifier = "dev" to Modifier = "rc.1"
• wait for CI
• merge PR
• trigger release
• if release failed - i need go to Devops and wait when they manually delete git tags, docker tags, etc... It bad practice to delete git tags. Why not just release rc.2 if rc.1 failed? Probably only because "again need create PR to app.go"
• wait for sync from scratch tests to pass

Need:

• simplify/automate/reduce_manual_steps_amount_because_i_alwayis_making_mistakes_there
• move more logic from .yml to erigon code. for example version check can be done inside erigon - where we can use some semver-complient library. It will allow: have unit-tests, manually test logic. For example here i vibecoded without much testing: https://github.com/erigontech/erigon/pull/20649/changes#diff-87db21a973eed4fef5f32b267aa60fcee5cbdf03c67fafdc2a9b553bb0b15f34R149

Related to: #20648