[Sprint] Use f-strings instead .format() function on asv/plugins/conda.py

[LucyJimenez]

xref #909

Since we support Python > 3.7 now, we can make use of f-strings, to make code more readable.

As an example, the next asv code:
machine_env_name = "{}/{}".format(machine, env_name)
or the next, which is equivalent:
machine_env_name = "{0}/{1}".format(machine, env_name)
Could be written as:
machine_env_name = f"{machine}/{env_name}"

(note the f before the string quotes)

---

The next command returns the list of strings to replace:

grep -R --exclude-dir="build" --exclude="*.css" ".format(" asv/plugins/conda.py

For this file, you will find the following issues to solve:

asv/plugins/conda.py:                        'python={0}'.format(python),
asv/plugins/conda.py:        log.info("Creating conda environment for {0}".format(self.name))
asv/plugins/conda.py:            conda_args = ['python={0}'.format(self._python), 'wheel', 'pip'] + conda_args
asv/plugins/conda.py:                           'channels:\n'.format(self.name))
asv/plugins/conda.py:                             "in {} with file {}".format(self._path, env_file_name))
asv/plugins/conda.py:                             "in {} with:\n{}".format(self._path, text))
asv/plugins/conda.py:                        pip_args.append("{0}=={1}".format(key[4:], val))
asv/plugins/conda.py:                        conda_args.append("{0}={1}".format(key, val))
asv/plugins/conda.py:        log.debug("Running '{0}' in {1}".format(' '.join(args), self.name))

[LucyJimenez]

@dorothykiz1 and @datapythonista, I'll work on this one.

[datapythonista]

Not useful anymore, and add noise to the issues list.