Add workaround for webpack builds on platforms unsupported by Sentry

[t3chguy]

$ webpack --progress --mode production
[webpack-cli] Failed to load '/builds/selfisekai/aports/community/element-web/src/element-web-1.11.55/webpack.config.js' config
[webpack-cli] Error: Unsupported operating system or architecture! Sentry CLI does not work on this architecture.
Sentry CLI supports:
- Darwin (macOS)
- Linux and FreeBSD on x64, x86, ia32, arm64, and arm architectures
- Windows x64, x86, and ia32 architectures

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This change is marked as an internal change (Task), so will not be included in the changelog.

[selfisekai]

lgtm