gh-35794: tox.ini, .github/workflows/docker.yml: Add almalinux
    
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### 📚 Description

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Particularly relevant because [manylinux_2_28](https://github.com/pypa/m
anylinux#manylinux_2_28-almalinux-8-based) is based on AlmaLinux 8.
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URL: #35794
Reported by: Matthias Köppe
Reviewer(s): Dima Pasechnik

Author: Release Manager

.github/workflows/docker.yml

@@ -50,6 +50,8 @@ on:
            "centos-7-devtoolset-gcc_11",
            "centos-stream-8-python3.9",
            "centos-stream-9-python3.9",
+           "almalinux-8-python3.9",
+           "almalinux-9-python3.11",
            "gentoo-python3.10",
            "gentoo-python3.11",
            "archlinux-latest",

tox.ini

@@ -308,6 +308,13 @@ setenv =
     centos-stream-8:  BASE_TAG=stream8
     centos-stream-9:  BASE_TAG=stream9
     #
+    # https://hub.docker.com/_/almalinux
+    #
+    almalinux:      SYSTEM=fedora
+    almalinux:      BASE_IMAGE=almalinux
+    almalinux:                                 IGNORE_MISSING_SYSTEM_PACKAGES=yes
+    almalinux-8:      BASE_TAG=8
+    almalinux-9:      BASE_TAG=9
     # https://hub.docker.com/r/sheerluck/sage-on-gentoo-stage4/tags
     #
     gentoo:      SYSTEM=gentoo