Fix abi3 wheel build issue when no Python interpreters found on host

[messense]

Fixes the following issue.

maturin.exe build -m maturin/test-crates/pyo3-pure/Cargo.toml --zig --target aarch64-unknown-linux-gnu
🔗 Found pyo3 bindings with abi3 support for Python ≥ 3.7
🐍 Not using a specific python interpreter
📡 Using build options bindings from pyproject.toml
📦 Built source distribution to D:\a\maturin-action\maturin-action\maturin\test-crates\pyo3-pure\target\wheels\pyo3_pure-2.1.2.tar.gz
thread 'main' panicked at 'assertion failed: !wheels.is_empty()', src\main.rs:337:13
stack backtrace:
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

for

maturin/src/build_context.rs

Lines 232 to 234 in d39ab1a

	if !cpythons.is_empty() {
	built_wheels.extend(self.build_binding_wheel_abi3(&cpythons, *major, *minor)?);
	}

We should refactor the whole python interpreters detection logic later, we have used several faking interpreters for similar purposes now.

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