fix(create-gatsby): Use legacy peer deps (#29856) (#29862)

* fix(create-gatsby): Use legacy peer deps * Update tests (cherry picked from commit a92b276) Co-authored-by: Matt Kane <matt@gatsbyjs.com>

Author: GatsbyJS Bot

packages/create-gatsby/src/__tests__/init-starter.ts

@@ -153,7 +153,15 @@ describe(`init-starter`, () => {
  )
  expect(execa).toBeCalledWith(
  `npm`,
- [`install`, `--loglevel`, `error`, `--color`, `always`, `one-package`],
+ [
+ `install`,
+ `--loglevel`,
+ `error`,
+ `--color`,
+ `always`,
+ `--legacy-peer-deps`,
+ `one-package`,
+ ],
  { stderr: `inherit` }
  )
  })

packages/create-gatsby/src/init-starter.ts

@@ -99,7 +99,7 @@ const setNameInPackage = async (
  delete packageJson.author
  }
 
- await fs.writeJSON(packageJsonPath, packageJson)
+ await fs.writeJSON(packageJsonPath, packageJson, { spaces: 2 })
 }
 
 // Executes `npm install` or `yarn install` in rootPath.
@@ -139,7 +139,11 @@ const install = async (
  reporter.success(`Installed Gatsby`)
  reporter.info(`${c.blueBright(c.symbols.pointer)} Installing plugins...`)
 
- await execa(`npm`, [`install`, ...config, ...packages], options)
+ await execa(
+ `npm`,
+ [`install`, ...config, `--legacy-peer-deps`, ...packages],
+ options
+ )
  await clearLine()
  }