* rust: Pin log version to =0.4.18

The 0.4.19 requires rustc 1.60, but currently we support 1.58.
Pinning it is not a big deal since it's development dependecy for
tests and examples.

* rust: Regenerate and update lib.rs

bindgen was updated again and changed something which resulted in
new output (seems like some internal constants are removed).

* pythemis: Add pyproject.toml

Since setup.py is deprecated, let's try moving to the pyproject.toml
and configuring it with the same data as in setup.py.

Use setuptools as a backend for no particular reasons ¯\_(ツ)_/¯,
just because the name is familiar and we have no reasons to not use
it or use something else.

Keep the old setup.py for backward compatibility so old systems can
try to build the package.

For now, keep 0.14.0, we will bump the version in another PR.

* makefile: Use pyproject.toml for installing pythemis

According to this [1] article, the correct command is

    pip install .

in the project's root. Let's try that. Also, the other option is

    python -m build --wheel

which builds the package but doesn't install it. We can provide
something like `pythemis_build` for it for example.

[1]: https://godatadriven.com/blog/a-practical-guide-to-setuptools-and-pyproject-toml/

* pythemis: Update classifiers to Python3.6+

With many hours and docker containers I tested that themis actually
works up to python 3.4. The other versions require some changes in
makefile so they are more like "grey area".

However, python3.5 is deprecated and it produces warning like
"DEPRECATION: Python 3.5 reached the end of its life on..." so many
libraries don't support it. Instead they start with 3.6 which will
do as well, I guess.

Though, actually python3.6 is also deprecated [1]. The same will be
true for python3.7 in a couple of days (Jun 27 2023), so the question
is, should we declare support of these versions?

[1]: https://devguide.python.org/versions/

* pythemis: Extend range of supported py versions

* Update changelog

* rust-themis: Update bindgen

It updated and broke something again 🤦

* rust-themis: Pin bindgen version

It is pretty unstable with its frequent releases, so let's pin it.

* Update changelog

* changelog: Add 0.15.0 summary

* themis-core: Update version

* pythemis: Update version

* pythemis: Fix 8-year old typo in AUTHORS :)

* rbthemis: Update version

* jsthemis: Update versions

* wasm-themis: Update versions

* android-themis: Update version

* rust-themis: Update versions

* react-native-themis: Update versions

* pythemis: https in AUTHORS

Co-authored-by: vixentael <[email protected]>

* rust-themis: Update bench versions

Somehow missed that.

* changelog: Forgot to mention rust 1.58

* changelog: Mention the new iteration count

---------

Co-authored-by: vixentael <[email protected]>

* Bump BoringSSL and fix makefile

This is not the latest BoringSSL version yet, because there are
a couple of fixes. So, treat it as the first. Here we also fix
our makefile because the BoringSSL team fixed bug with the strange
behaviour of absolute path to symbols.txt [1].

[1]: https://boringssl.googlesource.com/boringssl/+/8c75ed046f799f1d8b805036b1dea9c5ec0a0fb5%5E%21/#F0

* Bump BoringSSL and fix opaque EVP

As OpenSSL, BoringSSL made many types opaque, so it will require
updating some of the code to not use fields.

* Bump BoringSSL again and fix RSA

The same issue - RSA type became opaque, so we need to use accessors
similar to what Openssl had.

* Bump BoringSSL once more

This is (hoperfully) the last bump. This time without issues but
we will see what CI says.

* Make bignum_to_bytes accept const bignum*

It will prevent some of the warnings. This function doesn't mutate
bignum anyway.

* Update changelog

* boringssl: Bump once again

This are test values because we will move the tag. But for now,
let's just test it.

They will fail probably, but just out of curiosity let's try to run
the tests.

Solstice!