[Tests] Separated some of the dependency tests

- Marked slow, to avoid parallel execution

tests/test_plot/test_dep_downloader.py

@@ -85,6 +85,7 @@ def test_dep_rar(test_dir, caplog, monkeypatch):
     try_dependency(ctx, caplog, monkeypatch, compress.__doc__, 'rar', 'rar', bin_dir, use_wrapper=True)
 
 
+@pytest.mark.slow
 def test_dep_pytool(test_dir, caplog, monkeypatch):
     """ Check the pytool_downloader """
     # Create a context to get an output directory
@@ -93,6 +94,7 @@ def test_dep_pytool(test_dir, caplog, monkeypatch):
     try_dependency(ctx, caplog, monkeypatch, kibom.__doc__, 'kibom', 'pytool', bin_dir_py)
 
 
+@pytest.mark.slow
 def test_dep_rsvg(test_dir, caplog, monkeypatch):
     """ Check the rsvg_downloader """
     # Create a context to get an output directory
@@ -111,6 +113,7 @@ def test_dep_git(test_dir, caplog, monkeypatch):
     try_dependency(ctx, caplog, monkeypatch, downloader.__doc__+dep, 'git', 'git', bin_dir)
 
 
+@pytest.mark.slow
 def test_dep_gs(test_dir, caplog, monkeypatch):
     """ Check the git_downloader """
     # Create a context to get an output directory