Bump pglast from 3.4 to 3.8

[dependabot]

Bumps pglast from 3.4 to 3.8.

Changelog

Sourced from pglast's changelog.

3.8 (2021-12-28)

- Fix glitch in the AST extractor tool (`issue [#97](https://github.com/lelit/pglast/issues/97)`__)
__ lelit/pglast#97


Add Linux AArch64 wheel build support (PR [#95](https://github.com/lelit/pglast/issues/95)__), thanks to odidev
__ lelit/pglast#95


Fix type mismatch when using --remove-pg_catalog-from-functions (PR [#93](https://github.com/lelit/pglast/issues/93)__), thanks
to Boris Zentner
__ lelit/pglast#93


3.7 (2021-10-13)

• Update libpg_query to 13-2.1.0

3.6 (2021-10-09)

- Use latest libpg_query, to fix an error parsing ``PLpgSQL`` statements (`issue [#88](https://github.com/lelit/pglast/issues/88)`__)
__ lelit/pglast#88
3.5 (2021-09-26)

• Forward the special_functions option to substream, when concatenating items (issue [#89](https://github.com/lelit/pglast/issues/89)__)

  __ lelit/pglast#89

• Fix representation of floating point numbers without decimal digits (issue [#91](https://github.com/lelit/pglast/issues/91)__)

  __ lelit/pglast#91

• Produce Python 3.10 wheels, thanks to cibuildwheel 2.1.2

• Update libpg_query to 13-2.0.7

• New option --remove-pg_catalog-from-functions on the command line tool (PR [#90](https://github.com/lelit/pglast/issues/90)__), thanks to Boris Zentner

... (truncated)

Commits

• b2f17dc Release 3.8
• 2b5a872 Update CHANGES.rst
• 583de7c Merge PR #93
• e873859 Update CHANGES.rst
• 1a94f45 Merge PR #95
• a30400f Do not redefine the Expr class when extracting the ast
• d355d41 Use pycparser 2.21, readme-renderer 32.0, twine 3.7.1 and coverage 6.2
• e2ed6bd Remote old coverage.el, replaced by https://github.com/lelit/pycov-mode
• 4f97a46 Add Linux AArch64 wheel build support
• 8b13001 Release 3.7
• Additional commits viewable in compare view

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[dependabot]

Superseded by #637.