Bump master branch GNU Radio version

[ncorgan]

The master branch currently supports GNU Radio 3.7, an almost 7-year-old release that I had troubles compiling on my Ubuntu 20.04 setup. Once support is added for later GNU Radio releases, I propose bumping master up to the latest stable version and maintaining backport branches.

2023/04/30

First, these PR's will need to be reworked into their own branches.

• Migrate to support GNU Radio 3.9 #77
• Bump to gnuradio 3.10/3.11 #82

2023/05/02

Then, gr-3.8 and gr-3.9 need to be sync'ed up.

• Match their .clang-format files and reformat the contents to match. This will make porting changes practical.
• Clean up code
  • std::cout -> GNU Radio logging
  • No exit() calls from a shared library
  • Missing returns from non-void functions

[ncorgan]

Note: the master branch will require GNU Radio 3.10+, due to C++ GRC codegen only being sufficiently developed by this point.