Homebrewのエラー

Python update時、venvをリセットする時でたエラー

$ brew cleanup

で下記のWarningがありました。
Warning: Skipping python: most recent version 3.7.6_1 not installed

---

アップデートします。

$ brew upgrade

で下記のエラー...

	4: from /usr/local/Homebrew/Library/Homebrew/brew.rb:23:in `<main>'
	3: from /usr/local/Homebrew/Library/Homebrew/brew.rb:23:in `require_relative'
	2: from /usr/local/Homebrew/Library/Homebrew/global.rb:13:in `<top (required)>'
	1: from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require'
/System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require': cannot load such file -- active_support/core_ext/object/blank (LoadError)```

---

$ brew update-reset

で[ブランチのリセットとアップデート](https://stackoverflow.com/a/54913258/8762296)
```==> Fetching /usr/local/Homebrew...
==> Resetting /usr/local/Homebrew...
Branch 'master' set up to track remote branch 'master' from 'origin'.
Reset branch 'master'

brew upgrade

で問題なくアップデートしましたが、Warningもありました。

Building python from source

  The bottle needs the Apple Command Line Tools to be installed.
  You can install them, if desired, with:
    xcode-select --install```

----

$ xcode-select --install

でまだ下記のエラー...
`xcode-select: note: install requested for command line developer tools`

- [command line developer toolsをインストール](https://qiita.com/mym/items/8bc079b7d0f5f55c49dc)

以上で全部解決。