pykvfinder: Install pillow, contourpy and kiwisolver from wheels in tests

matplotlib pulls pillow>=8 into the test venv; PyPI's newest pillow
(13.0.0) has no riscv64 wheel, so pip fell back to its sdist, which
fails to build without libjpeg. Restrict the compiled matplotlib deps
to binaries so pip resolves to the registry's riscv64 wheels.

Author: luhenry

.github/workflows/build-pykvfinder.yml

@@ -77,7 +77,7 @@ jobs:
           CIBW_MANYLINUX_RISCV64_IMAGE: ${{ env.MANYLINUX_RISCV64_IMAGE }}
           CIBW_ENVIRONMENT_LINUX: >-
             PIP_EXTRA_INDEX_URL=https://pypi.riseproject.dev/simple/
-            PIP_ONLY_BINARY=numpy,matplotlib
+            PIP_ONLY_BINARY=numpy,matplotlib,pillow,contourpy,kiwisolver
 
       - uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a  # v7.0.1
         with: