fix: add missing CA certificates to Dockerfile.mockccc

[jonastheis]

1. Purpose or design rationale of this PR

Install ca-certificates as otherwise cert verification fails when connecting to L1 RPC when building the image with make mockccc_docker.

2. PR title

Your PR title must follow conventional commits (as we are doing squash merge for each PR), so it must start with one of the following types:

• [ ] build: Changes that affect the build system or external dependencies (example scopes: yarn, eslint, typescript)
• [ ] ci: Changes to our CI configuration files and scripts (example scopes: vercel, github, cypress)
• [ ] docs: Documentation-only changes
• [ ] feat: A new feature
• [x] fix: A bug fix
• [ ] perf: A code change that improves performance
• [ ] refactor: A code change that doesn't fix a bug, or add a feature, or improves performance
• [ ] style: Changes that do not affect the meaning of the code (white-space, formatting, missing semi-colons, etc)
• [ ] test: Adding missing tests or correcting existing tests

3. Deployment tag versioning

Has the version in params/version.go been updated?

• [x] This PR doesn't involve a new deployment, git tag, docker image tag, and it doesn't affect traces
• [ ] Yes

4. Breaking change label

Does this PR have the breaking-change label?

• [x] This PR is not a breaking change
• [ ] Yes