can't install requirements by Makefile

[Keisuke Se]

`*requirements` target name is wrong, isn't it?.

```
$ make pip-test-requirements
make: Nothing to be done for 'pip-test-requirements'.

$ make pip-test-requirements
Installing cloud-init test dependencies...
pip install -r "pip-test-requirements.txt" -q
Could not open requirements file: [Errno 2] No such file or directory: 'pip-test-requirements.txt'
Makefile:30: recipe for target 'pip-test-requirements' failed
make: *** [pip-test-requirements] Error 1
```

Makefile
```
pip-requirements:
    @echo "Installing cloud-init dependencies..."
    $(PIP_INSTALL) -r "$@.txt" -q

pip-test-requirements:
    @echo "Installing cloud-init test dependencies..."
    $(PIP_INSTALL) -r "$@.txt" -q
```

```
$ ls -l *requirements.txt
-rw-r--r-- 1 vagrant vagrant 948 11月 30 15:12 requirements.txt
-rw-r--r-- 1 vagrant vagrant 71 11月 30 15:12 test-requirements.txt
```

[Joshua Powers (powersj)]

Thank you for taking the time to report this bug. In an effort to keep
an up-to-date and valid list of bugs to work on, I have reviewed this
report verifying it still requires effort and occurs on a supported
version of Ubuntu.

It looks like you have a patch ready to go. Would you be willing to
submit a merge proposal with that patch? If so take a look at the
hacking document here:

https://cloudinit.readthedocs.io/en/latest/topics/hacking.html

Thanks!

[Brett Holman (holmanb)]

These targets no longer exist in the makefile, and these days we use tox rather than the Makefile.

Closing

[James Falcon (falcojr)]

Tracked in Github Issues as https://github.com/canonical/cloud-init/issues/2602