fix(ci): repair the release workflow's Windows version step

[docushell-dev]

`release.yml` has failed to parse since before the v0.6.0 work, so every push to `main` produces a red run with zero jobs. It went unnoticed because the workflow only triggers on `push: tags: ["v*"]` and nothing has been tagged — GitHub still creates a run and fails it at parse time.

The bug

The Windows "derive candidate version" step was a single-quoted YAML scalar, where `''` escapes a quote. `[''version']` had one quote too few, closing the scalar early:

```yaml
run: '"value=$(python -c "...open(''Cargo.toml'',''rb''))[''workspace''][''package''][''version'])")" | Out-File ...'
```

Fixing only the quote would have produced a workflow that parses and then fails at runtime: the same string used `"` as an escape inside a PowerShell double-quoted string, and pwsh escapes with a backtick or a doubled quote, not a backslash.

A block scalar removes both problems — no YAML quoting, and the PowerShell reads as ordinary PowerShell. The bash equivalent at line 57 was always correct because it is an unquoted scalar; this brings the Windows step to the same intent.

Verified

• All four workflow files parse
• This was the only pwsh step and the only quoted scalar with backslash escapes in the file
• The inner Python one-liner returns `0.6.0` against the current `Cargo.toml`

Not verified

Runtime behaviour on a Windows runner. `pwsh` is not available locally, and confirming it would require pushing a `v*` tag, which fires a real release. `Out-File` is left without an explicit `-Encoding` because `shell: pwsh` is PowerShell Core, which already writes UTF-8 without a BOM.

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