Fix Improper Import Order Breaking fuzz_submodule Fuzzer

ClusterFuzz runs of the `fuzz_submodule` target have been failing
because the `git` import was placed before the condition that sets the
Git executable path.

The order in which `git` is imported matters because it attempts to find
a Git executable as the import is loaded (via `refresh()` in
`git/__init__.py`.) As per gitpython-developers#1909, we configure the ClusterFuzz
environment to use a bundled Git executable via the env variable
condition in all fuzz targets.

fuzzing/fuzz-targets/fuzz_submodule.py

@@ -4,12 +4,13 @@
 import tempfile
 from configparser import ParsingError
 from utils import is_expected_exception_message, get_max_filename_length
-from git import Repo, GitCommandError, InvalidGitRepositoryError
 
 if getattr(sys, "frozen", False) and hasattr(sys, "_MEIPASS"):  # pragma: no cover
     path_to_bundled_git_binary = os.path.abspath(os.path.join(os.path.dirname(__file__), "git"))
     os.environ["GIT_PYTHON_GIT_EXECUTABLE"] = path_to_bundled_git_binary
 
+from git import Repo, GitCommandError, InvalidGitRepositoryError
+
 if not sys.warnoptions:  # pragma: no cover
     # The warnings filter below can be overridden by passing the -W option
     # to the Python interpreter command line or setting the `PYTHONWARNINGS` environment variable.