setup: use git version instead of hardcoded one

setuptool_scm [1] package is a recommended way to set package version
with git [2]. Version 5.0.2 was chosen due to Python 3.5 support,
latest version 7.0.5 supports only Python 3.7+.

Extract package version in documentation (see "Usage from Sphinx" in
[1]).

1. https://pypi.org/project/setuptools-scm/
2. https://packaging.python.org/en/latest/guides/single-sourcing-package-version/

Part of #238

Author: DifferentialOrange

Diff for: Makefile

@@ -1,4 +1,6 @@
 .PHONY: test docs
+install:
+	python setup.py install
 test:
 	python setup.py test
 testdata:

Diff for: README.rst

@@ -114,7 +114,14 @@ To build documentation, first you must install its build requirements:
 
     $ pip install -r docs/requirements.txt
 
-Then run
+To build with valid version, `tarantool` package must be installed before
+documentation build.
+
+.. code-block:: bash
+
+    $ make install
+
+Build documentation the documentation with
 
 .. code-block:: bash
 

Diff for: docs/requirements.txt

@@ -1,3 +1,4 @@
 sphinx==5.2.1
 sphinx-paramlinks==0.5.4
 sphinx-favicon==0.2
+importlib-metadata >= 1.0 ; python_version < '3.8'

Diff for: docs/source/conf.py

@@ -57,7 +57,14 @@
 # The version info for the project you're documenting, acts as replacement for
 # |version| and |release|, also used in various other places throughout the
 # built documents.
-#
+
+if sys.version_info >= (3, 8):
+    from importlib import metadata
+else:
+    import importlib_metadata as metadata
+
+__version__ = metadata.version('tarantool')
+
 # The short X.Y version.
 version = __version__
 # The full version, including alpha/beta/rc tags.

Diff for: setup.py

@@ -46,20 +46,11 @@ def get_dependencies():
             result = f.read().splitlines()
     return result
 
-def find_version(*file_paths):
-    version_file = read(*file_paths)
-    version_match = re.search(r"""^__version__\s*=\s*(['"])(.+)\1""",
-                              version_file, re.M)
-    if version_match:
-        return version_match.group(2)
-    raise RuntimeError("Unable to find version string.")
-
-
 setup(
     name="tarantool",
     packages=["tarantool"],
     package_dir={"tarantool": os.path.join("tarantool")},
-    version=find_version('tarantool', '__init__.py'),
+    use_scm_version=True,
     platforms=["all"],
     author="tarantool-python AUTHORS",
     author_email="[email protected]",
@@ -78,5 +69,8 @@ def find_version(*file_paths):
     cmdclass=cmdclass,
     command_options=command_options,
     install_requires=get_dependencies(),
+    setup_requires=[
+        'setuptools_scm==5.0.2',
+    ],
     python_requires='>=3',
 )

Diff for: tarantool/__init__.py

@@ -40,8 +40,6 @@
     Interval,
 )
 
-__version__ = "0.9.0"
-
 
 def connect(host="localhost", port=33013, user=None, password=None,
             encoding=ENCODING_DEFAULT, transport=DEFAULT_TRANSPORT,