Update gradle/actions/wrapper-validation from v3 to v4

[Copilot]

gradle/actions/wrapper-validation@v3 fetches its checksum validation database from services.gradle.org (Cloudflare-hosted) at runtime, causing intermittent ETIMEDOUT/ENETUNREACH failures in Linux CI runners. v4 ships with a bundled offline checksum database, eliminating the network dependency.

Changes

• .github/workflows/main.yml: bump all 4 gradle/actions/wrapper-validation usages from @v3 → @v4

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Gradle validation fails in linux actions</issue_title>
<issue_description>In github actions, the gradle validation steps sometimes fail on linux with

Run gradle/actions/wrapper-validation@v3
Error: Multiple errors returned
Error: Error 0: connect ETIMEDOUT 104.16.73.101:443
Error: connect ETIMEDOUT 104.16.73.101:443
    at createConnectionError (node:net:1652:14)
    at Timeout.internalConnectMultipleTimeout (node:net:1711:38)
    at listOnTimeout (node:internal/timers:583:11)
    at process.processTimers (node:internal/timers:519:7)
Error: Error 1: connect ENETUNREACH 2606:4700::6810:4965:443 - Local (:::0)
Error: connect ENETUNREACH 2606:4700::6810:4965:443 - Local (:::0)
    at internalConnectMultiple (node:net:1186:16)
    at Timeout.internalConnectMultipleTimeout (node:net:1716:5)
    at listOnTimeout (node:internal/timers:583:11)
    at process.processTimers (node:internal/timers:519:7)
Error: Error 2: connect ETIMEDOUT 104.16.72.101:443
Error: connect ETIMEDOUT 104.16.72.101:443
    at createConnectionError (node:net:1652:14)
    at Timeout.internalConnectMultipleTimeout (node:net:1711:38)
    at listOnTimeout (node:internal/timers:583:11)
    at process.processTimers (node:internal/timers:519:7)
Error: Error 3: connect ENETUNREACH 2606:4700::6810:4865:443 - Local (:::0)
Error: connect ENETUNREACH 2606:4700::6810:4865:443 - Local (:::0)
    at internalConnectMultiple (node:net:1186:16)
    at Timeout.internalConnectMultipleTimeout (node:net:1716:5)
    at listOnTimeout (node:internal/timers:583:11)
    at process.processTimers (node:internal/timers:519:7)

```</issue_description>

## Comments on the Issue (you are @copilot in this section)

<comments>
</comments>

• Fixes Gradle validation fails in linux actions #2650

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