Support libnacl v1.9.0 onward

libnacl.version file removed:

• https://github.com/saltstack/libnacl/commit/85e7b61b2c2dca957d5701c4cfc2b75fcdb46894

Get version with importlib.metadata.version("libnacl"):

• https://github.com/python-poetry/poetry/issues/273#issuecomment-570999678

Could have use pkg_resources.get_distribution("libnacl").version:

• https://github.com/python-poetry/poetry/issues/273#issuecomment-401983643

libnacl brought a breaking change, because it most likely does not follow semver versioning scheme.

duniterpy/key/ascii_armor.py

@@ -14,11 +14,11 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import base64
+import importlib.metadata
 import re
 from typing import Any, Dict, List, Optional
 
 import libnacl
-from libnacl.version import version as libnacl_version
 
 from .encryption_key import PublicKey
 from .signing_key import SigningKey
@@ -33,6 +33,7 @@ HEADER_PREFIX = "-----"
 DASH_ESCAPE_PREFIX = "\x2D\x20"
 
 # Version field value
+libnacl_version = importlib.metadata.version("libnacl")
 VERSION_FIELD_VALUE = f"Python Libnacl {libnacl_version}"
 
 # Parser cursor status