fix(deps): update ghcr.io/containerbase/base docker tag to v14.6.21

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
ghcr.io/containerbase/base		patch	14.6.20 → 14.6.21
ghcr.io/containerbase/base	stage	patch	14.6.20 → 14.6.21

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Release Notes

containerbase/base (ghcr.io/containerbase/base)

v14.6.21

Compare Source

Bug Fixes

• bun: use baseline if current amd64 cpu is missing avx2 (#​6434) (9994cc6)

Tests

• deps: update dependency composer to v2.9.7 (main) (#​6433) (42617d7)
• deps: update dependency conan to v2.27.1 (main) (#​6430) (3438bdb)
• deps: update dependency mise to v2026.4.11 (main) (#​6417) (aa2993a)
• deps: update dependency mise to v2026.4.11 (main) (#​6431) (f5deeae)

Miscellaneous Chores

• deps: update containerbase/internal-tools action to v4.5.20 (main) (#​6432) (564df3e)
• deps: update dependency prettier to v3.8.2 (main) (#​6426) (9a0f6ac)
• deps: update ghcr.io/containerbase/devcontainer docker tag to v14.6.20 (main) (#​6428) (d61af5e)

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