Cleanup pnpm overrides

* Pnpm has started wanting to update `@storybook/builder-webpack5`
  with every upstream release. Giving the relevant overrides a version
  makes it stick with the lockfile.
* `@automattic/format-currency` seems a bit outdated. We can clean up a
  lot of the old deps we have in pnpm-lock.yaml by updating its dep on
  `i18n-calypso` from 4.x to 5.x, and in turn updating `i18n-calypso`'s
  dep on `interpolate-components` 1.1.0 too.
* `jest-environment-enzyme` is [supposedly not dead][1], but still isn't
  being updated for several months. For our purposes at least it seems
  to work fine with jest-environment-jsdom 27.
* Looks like we've dropped the dep on whatever old version of
  `terser-webpack-plugin` had a dep on an old version of
  `serialize-javascript`, so drop the override.

[1]: enzymejs/enzyme-matchers#353

package.json

@@ -92,16 +92,16 @@
 	},
 	"pnpm": {
 		"overrides": {
-			"@storybook/addon-docs>@storybook/builder-webpack4": "npm:@storybook/builder-webpack5",
+			"@automattic/format-currency>i18n-calypso": "^5",
+			"@storybook/addon-docs>@storybook/builder-webpack4": "npm:@storybook/builder-webpack5@^6",
 			"@storybook/core-common>webpack@4": ">= 4",
 			"@storybook/core-server>webpack@4": ">= 4",
-			"@storybook/core-server>@storybook/builder-webpack4": "npm:@storybook/builder-webpack5",
-			"@storybook/core-server>@storybook/manager-webpack4": "npm:@storybook/manager-webpack5",
+			"@storybook/core-server>@storybook/builder-webpack4": "npm:@storybook/builder-webpack5@^6",
+			"@storybook/core-server>@storybook/manager-webpack4": "npm:@storybook/manager-webpack5@^6",
 			"@storybook/react>webpack@4": ">= 4",
-			"isomorphic-fetch>node-fetch@^1.0.1": "^2.6.1",
-			"jest-environment-jsdom@^24.0.0": "^26.0.1",
+			"i18n-calypso>interpolate-components": "npm:@automattic/interpolate-components@^1.2.0",
+			"jest-environment-enzyme>jest-environment-jsdom@^24.0.0": "^27",
 			"react-dev-utils>browserslist@^4": "^4",
-			"terser-webpack-plugin>serialize-javascript@^4.0.0": "^5.0.0",
 			"trim@0.0.1": "^0.0.3",
 			"yargs>yargs-parser@^5.0.1": "^20.0.0"
 		}