skip install related tests if git is missing (#10809)

tests/func/test_install.py

@@ -4,12 +4,13 @@ import sys
 
 import pytest
 from dulwich.porcelain import remote_add as git_remote_add
-from git import GitCommandError
 
 from dvc.exceptions import DvcException
 from dvc_data.hashfile.hash import file_md5
 from tests.func.parsing.test_errors import escape_ansi
 
+git = pytest.importorskip("git")
+
 
 @pytest.mark.skipif(
     sys.platform == "win32", reason="Git hooks aren't supported on Windows"
@@ -55,7 +56,7 @@ class TestInstall:
         dvc.install()
 
         # scm.commit bypasses hooks
-        with pytest.raises(GitCommandError, match=r"modified:\s*file"):
+        with pytest.raises(git.GitCommandError, match=r"modified:\s*file"):
             scm.gitpython.repo.git.commit(m="file modified")
 
     def test_post_checkout(self, tmp_dir, scm, dvc):