build: enable isolatedModules in ts-jest config to fix compiler warning

[mojito317]

PR summary

This configuration vanishes the following compiler warning:

(WARN) message TS151002: Using hybrid module kind (Node16/18/Next) is only supported in "isolatedModules: true". 
Please set "isolatedModules: true" in your tsconfig.json.
To disable this message, you can set "diagnostics.ignoreCodes" to include 151002 in your ts-jest config.
See more at https://kulshekhar.github.io/ts-jest/docs/getting-started/options/diagnostics

See also:
kulshekhar/ts-jest#5013
https://huafu.github.io/ts-jest/user/config/isolatedModules

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PR Checklist

Please make sure that your PR fulfills the following requirements:

• The commit message follows the
  Angular Commit Message Guidelines.
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• New tests
• Build/CI related changes
• Documentation content changes
• Other (please describe)

What is the current behavior?

What is the new behavior?

Does this PR introduce a breaking change?

• Yes
• No

Other information

[mojito317]

I am closing this as we agreed offline to wait for the next major version of ts-jest before applying anything.