fix: Make mail-parser really optional

pymisp/tools/__init__.py

@@ -12,16 +12,22 @@ from .asnobject import ASNObject  # noqa
 from .geolocationobject import GeolocationObject  # noqa
 from .git_vuln_finder_object import GitVulnFinderObject  # noqa
 
-from .emailobject import EMailObject  # noqa
+try:
+    from .emailobject import EMailObject  # noqa
+except ImportError:
+    # Requires mail-parser, which requires perl packages, optional [email]
+    pass
+
 from .vehicleobject import VehicleObject  # noqa
 from .csvloader import CSVLoader  # noqa
 from .sshauthkeyobject import SSHAuthorizedKeysObject  # noqa
 from .feed import feed_meta_generator  # noqa
 from .update_objects import update_objects  # noqa
+
 try:
     from .urlobject import URLObject  # noqa
 except ImportError:
-    # Requires faup, which is a bit difficult to install
+    # Requires pyfaup, optional dependency [url]
     pass
 except OSError:
     # faup required liblua-5.3
@@ -32,5 +38,5 @@ try:
     from .elfobject import ELFObject, ELFSectionObject  # noqa
     from .machoobject import MachOObject, MachOSectionObject  # noqa
 except ImportError:
-    # Requires lief, which is a bit difficult to install
+    # Requires lief, optional [fileobjects]
     pass