[wasm] Bump CPython to v3.13.3 for Emsdk 5.0.6

[pavelsavara]

Contributes to dotnet/runtime#113786

Summary

Bumps dotnet/cpython to upstream python/cpython tag v3.13.3 at ac3d5eaec2d0.

Branch contents

https://github.com/pavelsavara/cpython/commits/bump-python-3.13.3/

• Fresh from upstream tag (no merge, clean history)
• Drop tests, docs, benchmarks, MSI tooling for scan-area reduction (2,562 files)
• Add Arcade scaffolding + cpython 3.13.3 version refs + Linux build support
• New: --disable-test-modules configure flag, guarded OpenSSL/lipo with Condition="' == 'OSX'"
• Policy merge from dotnet/main (-s ours): establishes common ancestor with dotnet/main while keeping 3.13.3 content
• Restore latest Arcade scaffolding from dotnet/main (May 2026)

Merge strategy

The previous dotnet/main was based on CPython 3.11. This PR replaces it entirely with 3.13.3.
A policy merge (git merge -s ours) was used to establish dotnet/main as an ancestor so GitHub can merge cleanly. The tree content is 100% from the 3.13.3 branch (plus Arcade scaffolding restored from latest dotnet/main).

Validation

• linux-x64 build from source + pack succeeded (0 errors)
• Package: runtime.linux-x64.Microsoft.NETCore.Runtime.Wasm.Python.Transport.11.0.0-alpha.1.26253.2.nupkg (30M)

Note

Emsdk does NOT consume a Linux Python transport package (uses system python3). Python transport packages are only for macOS and Windows.