fix cross-fetch moderate vulnerability alert

[brad-decker]

Explanation

yarn-audit is failing due to vulnerability: https://github.com/MetaMask/metamask-extension/security/dependabot/66 in cross-fetch. This PR sets a resolution for cross-fetch to 3.1.5 or higher

[metamaskbot]

Builds ready [529e84e]

• builds: chrome, firefox, opera
• builds (beta): chrome, firefox, opera
• builds (flask): chrome, firefox, opera
• build viz: Build System
• code coverage: Report
• storybook: Storybook
• all artifacts
• bundle viz:

  • background: 0, 1, 2, 3, 4, 5, 6, 7
  • common: 0, 1, 2, 3, 4, 5, 6, 7, 8
  • content-script: 0
  • contentscript: contentscript
  • disable-console: disable-console
  • inpage: inpage
  • phishing-detect: phishing-detect
  • policy-load: policy-load
  • sentry-install: sentry-install
  • ui: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9

Page Load Metrics (1779 ± 51 ms)

Platform	Page	Metric	Min (ms)	Max (ms)	Average (ms)	StandardDeviation (ms)	MarginOfError (ms)
Chrome	Home	firstPaint	80	1708	177	351	169
		domContentLoaded	1639	1997	1752	91	44
		load	1639	1997	1779	106	51
		domInteractive	1639	1997	1752	91	44

[rekmarks]

LGTM!