chore: replaced banner svg with png version to support vsce bundling

[Phillip9587]

I missed that vsce does not support SVGs in README:

nps is executing `package.vscode` : shx rm -rf dist/apps/vscode/**/*-es5.js && node tools/scripts/vscode-vsce.js
ERROR  SVGs are restricted in README.md; please use other file image formats, such as PNG: https://raw.githubusercontent.com/nrwl/nx-console/master/static/nx-console-banner.svg

[nx-cloud]

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CI ran the following commands for commit c2af2ae. Click to see the status, the terminal output, and the build insights.

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✅ Successfully ran 3 targets

• nx run-many --all --parallel --target=build --max-parallel=3
• nx run-many --all --parallel --target=test --max-parallel=3
• nx run-many --all --parallel --target=lint --max-parallel=3

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