Support RHEL/Rocky/AlmaLinux 9 & 10 and Fedora via the Debian 12 binary

[vliggio]

Summary

Adds support for RHEL 9/10 and clones, plus Fedora, by mapping them to the existing Debian 12 binary. No new binaries are bundled — this follows the same approach as the recent "Debian 13 → Debian 12" change.

Fixes #191 (Rocky/RHEL/AlmaLinux 9 — also covers 10), #169 (CentOS Stream 9), and #182 (Fedora).

Why the Debian 12 binary (not CentOS 8)?

The RHEL-8 family already maps to the CentOS 8 binary. But RHEL 9/10 and their clones (Rocky, AlmaLinux, Oracle Linux, CentOS Stream), as well as modern Fedora, ship OpenSSL 3 + a newer glibc:

• the CentOS 8 binary links libssl.so.1.1, which is absent on these systems;
• the Debian 12 binary links libssl.so.3, which is present.

This matches the ldd output the reporter posted in #191 confirming the Debian 12 binary resolves cleanly on Rocky Linux 9.6.

Changes

• bin/wkhtmltopdf — map rocky_9/10, rhel_9./10., ol_9./10., almalinux_9/10, centos_9/10, and fedora* → debian_12; update the platform error message.
• .docker/ — new Dockerfiles for rockylinux_9, almalinux_9, rockylinux_10, almalinux_10, and fedora.
• docker-compose.yml + test/test_with_docker.rb — services and tests for the above.

Supersedes #186

Open PR #186 ("support centos 9") also targets the CentOS 9 case (#169), but maps centos_9 → the centos_8 binary. That binary links libssl.so.1.1, which is absent on CentOS Stream 9 (OpenSSL 3), so it would still fail at runtime. This PR maps centos_9 → debian_12 (OpenSSL 3) instead, which is the working fix — so #186 can be closed in favor of this.

Issues reviewed but not changed

• Add AlmaLinux Support #158 (AlmaLinux 8) is already resolved by the existing almalinux_8 → centos_8 mapping (0.12.6.8); verified no regression.

Notes

• The Fedora mapping is a broad fedora* match — correct for every in-support Fedora (all ship OpenSSL 3). Pre-OpenSSL-3 Fedora (≤35, all EOL) can still use WKHTMLTOPDF_HOST_SUFFIX.
• The Fedora Dockerfile pins fedora:42 (a supported release) rather than the EOL fedora:40 from not working on fedora 40 #182, since EOL tags break dnf install against archived mirrors. The mapping covers 40 regardless.
• I left the version bump / CHANGELOG entry out, matching the maintainer's convention of handling those in a separate release commit.

🤖 Generated with Claude Code

[vliggio]

@unixmonkey please take a look and see if this works for a new version of this gem. Thanks!