Remove PowerPC wheels for LQ (#902)

### Before submitting

Please complete the following checklist when submitting a PR:

- [ ] All new features must include a unit test.
If you've fixed a bug or added code that should be tested, add a test to
the
      [`tests`](../tests) directory!

- [ ] All new functions and code must be clearly commented and
documented.
If you do make documentation changes, make sure that the docs build and
      render correctly by running `make docs`.

- [ ] Ensure that the test suite passes, by running `make test`.

- [ ] Add a new entry to the `.github/CHANGELOG.md` file, summarizing
the
      change, and including a link back to the PR.

- [ ] Ensure that code is properly formatted by running `make format`. 

When all the above are checked, delete everything above the dashed
line and fill in the pull request template.


------------------------------------------------------------------------------------------------------------

**Context:**
Remove PowerPC wheel recipe for Lightning-Qubit. Users can still install
LQ from source by following [the installation
guideline](https://docs.pennylane.ai/projects/lightning/en/stable/lightning_qubit/installation.html):

``` console
pip install pennylane-lightning --no-binary :all:
```

**Description of the Change:**
- Remove `.github/workflows/wheel_linux_ppc64le.yml`
- Update README
 
**Benefits:**
Reduce the number of wheels recipes and CI checks per PR. We can revert
this if it turns out that many rely on these wheels.

**Possible Drawbacks:**
PowerPC wheels will not be built and uploaded to PyPI and TestPyPI
starting with v0.39.0

**Related GitHub Issues:**

---------

Co-authored-by: ringo-but-quantum <github-ringo-but-quantum@xanadu.ai>

.github/CHANGELOG.md

@@ -13,8 +13,11 @@
 
 ### Breaking changes
 
+* Remove PowerPC wheel build recipe for Lightning-Qubit.
+  [(#902)](https://github.com/PennyLaneAI/pennylane-lightning/pull/902)
+
 * Remove support for Python 3.9.
-  [#891](https://github.com/PennyLaneAI/pennylane-lightning/pull/891)
+  [(#891)](https://github.com/PennyLaneAI/pennylane-lightning/pull/891)
 
 ### Improvements
 
@@ -33,7 +36,7 @@
 * Smarter defaults for the `split_obs` argument in the serializer. The serializer splits linear combinations into chunks instead of all their terms.
   [(#873)](https://github.com/PennyLaneAI/pennylane-lightning/pull/873/)
 
-* Unify Lightning Kokkos device and Lightning Qubit device under a Lightning Base device
+* Unify Lightning-Kokkos device and Lightning-Qubit device under a Lightning Base device.
   [(#876)](https://github.com/PennyLaneAI/pennylane-lightning/pull/876)
 
 ### Documentation

README.rst

@@ -62,7 +62,7 @@ The following table summarizes the supported platforms and the primary installat
 +-----------+---------+--------+-------------+----------------+-----------------+----------------+----------------+
 | Linux ARM | pip     | pip    |             | pip            | source          | source         |                |
 +-----------+---------+--------+-------------+----------------+-----------------+----------------+----------------+
-| Linux PPC | pip     | source |             | pip            | source          | source         |                |
+| Linux PPC | pip     | source |             | source         | source          | source         |                |
 +-----------+---------+--------+-------------+----------------+-----------------+----------------+----------------+
 | MacOS x86 | pip     |        |             | pip            |                 |                |                |
 +-----------+---------+--------+-------------+----------------+-----------------+----------------+----------------+

pennylane_lightning/core/_version.py

@@ -16,4 +16,4 @@
    Version number (major.minor.patch[-label])
 """
 
-__version__ = "0.39.0-dev11"
+__version__ = "0.39.0-dev12"