libpri: update to version 1.6.1

libpri: update to version 1.6.1

Allows to drop backport patch which is now part of the new release.

Change Log for Release libpri-1.6.1
========================================

Links:
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 - [Full ChangeLog](https://downloads.asterisk.org/pub/telephony/libpri/releases/ChangeLog-1.6.1.md)
 - [GitHub Diff](https://github.com/asterisk/libpri/compare/1.6.0...1.6.1)
 - [Tarball](https://downloads.asterisk.org/pub/telephony/libpri/libpri-1.6.1.tar.gz)
 - [Downloads](https://downloads.asterisk.org/pub/telephony/libpri)

Summary:
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- .github: Add Releaser workflow
- Link README to README.md
- Makefile: Fix modern compiler errors.
- Makefile: Add the ability to build libpri on MacOS for Linux target.
- q931.c: Fix subaddress finding octet 4.

User Notes:
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Upgrade Notes:
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Closed Issues:
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None

Commits By Author:
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- ### George Joseph (2):
  - Link README to README.md
  - .github: Add Releaser workflow

- ### Sean Bright (1):
  - Makefile: Fix modern compiler errors.

- ### Sergey V. Lobanov (1):
  - Makefile: Add the ability to build libpri on MacOS for Linux target.

- ### bbabic (1):
  - q931.c: Fix subaddress finding octet 4.

Detail:
----------------------------------------

- ### .github: Add Releaser workflow
  Author: George Joseph
  Date:   2023-08-16

- ### Link README to README.md
  Author: George Joseph
  Date:   2023-08-15

- ### Makefile: Fix modern compiler errors.
  Author: Sean Bright
  Date:   2023-03-10

  Disable GCC's zero-length-bounds and stringop-overflow errors.

  PRI-189 #close

- ### Makefile: Add the ability to build libpri on MacOS for Linux target.
  Author: Sergey V. Lobanov
  Date:   2022-02-19

  This patch allows to redefine ar and ranlib tool using AR and
  RANLIB make flags.

  PRI-188 #close

- ### q931.c: Fix subaddress finding octet 4.
  Author: bbabic
  Date:   2017-10-23

  Some switches have extended subaddress ie octet 3 encoding to be
  multi-octet.

  * Update dump and receive helper functions to search for the end of octet
  3 encoding to determine where octet 4 starts.

  ASTERISK-27342

Signed-off-by: Daniel Golle <[email protected]>