Wheels: Keep Python 3.8 for now

WarpX CI still uses it.

x-ref: openPMD#1677 openPMD#1554

.github/workflows/build.yml

@@ -105,7 +105,7 @@ jobs:
         #     https://github.com/pypa/manylinux/issues/899
         CIBW_SKIP: "pp*-manylinux*"
         CIBW_ARCHS: "${{ matrix.arch }}"
-        CIBW_PROJECT_REQUIRES_PYTHON: ">=3.9"
+        CIBW_PROJECT_REQUIRES_PYTHON: ">=3.8"
         # Install dependencies
         CIBW_BEFORE_BUILD_LINUX: bash -x .github/library_builders.sh
         CIBW_BEFORE_BUILD_MACOS: bash -x .github/library_builders.sh

.travis.yml

@@ -28,7 +28,7 @@ jobs:
       arch: arm64
       dist: focal
       env:
-        - CIBW_BUILD="cp39-manylinux_aarch64"
+        - CIBW_BUILD="cp38-manylinux_aarch64 cp39-manylinux_aarch64"
     - services: docker
       arch: arm64
       dist: focal
@@ -48,13 +48,13 @@ jobs:
       arch: arm64
       dist: focal
       env:
-        - CIBW_BUILD="pp39-manylinux_aarch64"
+        - CIBW_BUILD="pp38-manylinux_aarch64 pp39-manylinux_aarch64"
     # +musllinux
     - services: docker
       arch: arm64
       dist: focal
       env:
-        - CIBW_BUILD="cp39-musllinux_aarch64"
+        - CIBW_BUILD="cp38-musllinux_aarch64 cp39-musllinux_aarch64"
     - services: docker
       arch: arm64
       dist: focal
@@ -67,6 +67,11 @@ jobs:
         - CIBW_BUILD="cp312-musllinux_aarch64 cp313-musllinux_aarch64"
 
     # perform a linux PPC64LE build
+    - services: docker
+      arch: ppc64le
+      dist: focal
+      env:
+        - CIBW_BUILD="cp38-manylinux_ppc64le"
     - services: docker
       arch: ppc64le
       dist: focal
@@ -92,6 +97,11 @@ jobs:
       dist: focal
       env:
         - CIBW_BUILD="cp313-manylinux_ppc64le"
+    - services: docker
+      arch: ppc64le
+      dist: focal
+      env:
+        - CIBW_BUILD="cp38-musllinux_ppc64le"
     - services: docker
       arch: ppc64le
       dist: focal