Update web with SV-COMP 2026 and Test-COmp 2026 results

Integrate all svcomp25 changes (#267)

Use upstream JetKlee

Use upstream sbt-instrumentation. (#264)

Use upstream sbt-slicer. (#263)

Use upstream dg (#265)

CI: add LLVM14 job (#262)

CI: replace Ubuntu 20.04 with Ubuntu 22.04 (#259)

Update index.md with Test-Comp 2024 and 2025 participation and medals

Update index.md with SV-COMP 2025 participations and medals

add SV-COMP 2024 medals and publication to index.md

Update team.md

CI: replace Ubuntu 18.04 with Ubuntu 20.04

CI: do not use deprecated set-output syntax

system-build: remove dependency on curl since it is unused