Update Ubuntu Docker image to 26.04 #4829

Job	Run time
pre-commit / link-check	15s
pre-commit / pre-commit	2m 4s
ci-scope	5s
mac / clang-build (Release)	2m 19s
windows / msvc-build (Release)	2m 21s
mac / clang-build (Debug)	1m 46s
ubuntu / gcc-build (ubuntu-24.04, Debug)	2m 6s
windows / msvc-build (Debug)	5m 27s
windows / clang-build	3m 0s
ubuntu / clang-build (ubuntu-24.04)	2m 45s
ubuntu / gcc-build (ubuntu-24.04, Release)	2m 10s
ubuntu / gcc-test (ubuntu-24.04)	8m 37s
mac / clang-test	4m 16s
ubuntu / clang-test (ubuntu-24.04)	8m 35s
ubuntu / clang-sanitizer-build (ubuntu-24.04)	3m 19s
windows / clang-test	2m 54s
windows / msvc-test	4m 49s
windows / clang-test-extended	3m 8s
ubuntu / clang-sanitizer-test (ubuntu-24.04)	2m 59s
mac / clang-test-extended	3m 4s
ubuntu / clang-sanitizer-test-extended (ubuntu-24.04)	2m 28s
windows / msvc-test-extended	3m 24s
ubuntu / gcc-test-extended (ubuntu-24.04)	4m 44s
ubuntu / clang-test-extended (ubuntu-24.04)	4m 42s
ubuntu / gcc-build-codecov	8m 11s
perf / ubuntu-gcc-build-perf-stats	1m 27s
perf / macos-clang-build-perf-stats	1m 58s
pages / build-scoreboard	16s
pages / build-doxygen-xml	17s
pages / build-sphinx	40s
pages / deploy-pages	0s
	1h 34m 6s

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