MacOS Cataline で psutil のインストールに失敗

# 環境

- macOS Cataline 10.15.1
- psutil==5.7.0

[psutil](https://github.com/giampaolo/psutil)は、実行中のプロセスやシステムの利用状況をPythonで取得するためのクロスプラットフォームライブラリ。


# 状況

`psutil` を poetryでインストールしようとしたところ、大量のエラーメッセージと共に失敗。

```bash
$ poetry install --no-root
Installing dependencies from lock file

Package operations: 35 installs, 0 updates, 0 removals

  - Installing psutil (5.7.0)

    clang -Wno-unused-result -Wsign-compare -Wunreachable-code -DNDEBUG -g -fwrapv -O3 -Wall -I/Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk/usr/include -I/Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk/usr/include -DPSUTIL_POSIX=1 -DPSUTIL_SIZEOF_PID_T=4 -DPSUTIL_VERSION=570 -DPSUTIL_OSX=1 -I/Users/hinata/.ghq/github.com/Nikkei/b2b-api-article/.venv/include -I/Users/hinata/.pyenv/versions/3.8.2/include/python3.8 -c psutil/_psutil_common.c -o build/temp.macosx-10.14-x86_64-3.8/psutil/_psutil_common.o
    In file included from psutil/_psutil_common.c:9:
    In file included from /Users/hinata/.pyenv/versions/3.8.2/include/python3.8/Python.h:25:
    In file included from /Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk/usr/include/stdio.h:64:
    /Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk/usr/include/_stdio.h:93:16: warning: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness]
            unsigned char   *_base;
                            ^
    /Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk/usr/include/_stdio.h:93:16: note: insert '_Nullable' if the pointer may be null
            unsigned char   *_base;
                            ^
                              _Nullable
    /Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk/usr/include/_stdio.h:93:16: note: insert '_Nonnull' if the pointer should never be null
            unsigned char   *_base;
                            ^
                              _Nonnull
    /Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk/usr/include/_stdio.h:138:32: warning: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness]
            int     (* _Nullable _read) (void *, char *, int);
                                              ^
    /Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk/usr/include/_stdio.h:138:32: note: insert '_Nullable' if the pointer may be null
            int     (* _Nullable _read) (void *, char *, int);
                                              ^
                                               _Nullable
    /Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk/usr/include/_stdio.h:138:32: note: insert '_Nonnull' if the pointer should never be null
            int     (* _Nullable _read) (void *, char *, int);
                                              ^
                                               _Nonnull
    /Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk/usr/include/_stdio.h:138:40: warning: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness]
            int     (* _Nullable _read) (void *, char *, int);
                                                      ^
```

MacOSX10.14.sdk周りでたくさん怒られるている。

# 原因

自分のCatalineのバージョンは10.15なので、変だなと思い潜ってるとsdkが２つ存在していてた。 


```sh
$ cd /Library/Developer/CommandLineTools/SDKs
$ ls 
MacOSX.sdk      MacOSX10.14.sdk MacOSX10.15.sdk
```

10.14を消したら無事インストールできた。古いものが残っていて干渉を起こしていたようだ。

```
$ ls sudo rm -rf MacOSX10.14.sdk
Password:
$ ls
MacOSX.sdk      MacOSX10.15.sdk
```