Add acorn as explicit dependency

[tomlinton]

First pull request? Read our guide to contributing

Description:

• New version of webpack has broken deps: Parsing of import() fails in 4.29.0 (Compilation issue, related to dynamic import) webpack/webpack#8656
• Fixed by adding acorn as explicit dependency

Checklist:

• Test your work and double-check to confirm that you didn't break anything
• Wrap any displayed ETH addresses with formattedAddress
• Wrap any new text/strings for translation
• Map any new environment variables with a default value in the Webpack config
• Update any relevant READMEs and docs

[micahalcorn]

🌰