chore: bump minor rather than major for pre-1.0 breaking changes (#73)

Adds `bump-minor-pre-major: true` to the release-please config, matching
the Ruby provider repo's configuration.

**Why:** release-please's default versioning strategy escalates a
breaking change to a major bump even below 1.0.0. The `fix!:` in #64
therefore retitled the open release PR #72 to **1.0.0** instead of
**0.9.0**. Crossing to 1.0 should be a deliberate GA decision, not a
side effect of a missing config flag.

**Effect:** merging this PR triggers a release-please run, which will
recompute #72 to 0.9.0 (a `Release-As: 0.9.0` override has also been
added to #64's body as a belt-and-suspenders measure — both mechanisms
agree). The changelog is unchanged and the release remains flagged as
breaking.

With this flag, pre-1.0 breaking changes bump the minor (0.x → 0.(x+1))
going forward.

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Overview**
> Adds **`bump-minor-pre-major`: true** to `release-please-config.json`
so release-please treats breaking changes as **minor** bumps while the
package is still below **1.0.0**, instead of jumping to **1.0.0** by
default.
> 
> This aligns versioning with the Ruby provider repo and keeps a
deliberate **1.0.0** GA cut separate from conventional-commit breaking
changes (e.g. retitling an in-flight release PR from **1.0.0** to
**0.9.0** without changing the breaking changelog content).
> 
> <sup>Reviewed by [Cursor Bugbot](https://cursor.com/bugbot) for commit
ae994ba. Bugbot is set up for automated
code reviews on this repo. Configure
[here](https://www.cursor.com/dashboard/bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: tanderson-ld

release-please-config.json

@@ -3,6 +3,7 @@
     ".": {
       "release-type": "python",
       "versioning": "default",
+      "bump-minor-pre-major": true,
       "include-v-in-tag": false,
       "extra-files": ["docs/conf.py", "ld_openfeature/version.py"],
       "include-component-in-tag": false