[shreemaan-abhishek]

Description

Bumps APISIX_RUNTIME from 1.4.1 to 1.4.2, with the version guard and the two apisix-runtime-debug checksums in ci/linux-install-openresty.sh.

What moves in apisix-runtime 1.4.2:

Component	1.4.1	1.4.2
OpenResty (nginx)	1.31.1.1 (1.31.1)	1.31.8.1 (1.31.8)
OpenSSL	3.5.9	3.5.9
apisix-nginx-module	1.20.1	1.20.3 (api7/apisix-nginx-module#136, #139)
ngx_multi_upstream_module	1.4.0	1.4.1 (api7/ngx_multi_upstream_module#24)

• Security: nginx 1.31.8 carries the security fixes released since nginx 1.31.1.
• gzip: apisix-nginx-module 1.20.2 fixes gzip compression when the gzip plugin's buffers.size is smaller than the page size.
• Dubbo: ngx_multi_upstream_module 1.4.1 fixes 500s on multiplexed upstream connections that connect immediately (unix sockets) or are still connecting when a second request reuses them.

t/core/runtime-version.t now asserts nginx 1.31.8 or newer.

Checksums were taken from the published release artifacts:

0fdc20431fac3509093b7f1f935343796db8c0309726a711249bc2a9468fca33  apisix-runtime-debug_1.4.2-0.debianbookworm-slim_amd64.deb
82a44e73b47b94d7fcb80641f202efa4154ece6bf4719838bb7fe2434e581fa0  apisix-runtime-debug_1.4.2-0.debianbookworm-slim_arm64.deb

Which issue(s) this PR fixes:

N/A

Checklist

• I have explained the need for this PR and the problem it solves
• I have explained the changes or the new features added to this PR
• I have added tests corresponding to this change
• I have updated the documentation to reflect this change
• I have verified that this change is backward compatible (If not, please discuss on the APISIX mailing list first)