Release ReBench 1.2: Custom Gauge Adapters & Dropped Python 2 Support

[smarr]

The main feature of this release is the new support for custom gauge adapters. This allows the use of a Python file from the ReBench config, which can parse arbitrary output from a benchmark, see #209.

Furthermore, ReBench dropped support for Python 2. If you require ReBench to run with Python 2, please see #208 for the removed supported code, or use version 1.1.0, which was the last version with Python 2 support.

Other new features:

• add command-line option -D to disable the use of denoise (Add option to disable denoise #217)
• include CSV headers into .data files (Include CSV header in data files #220, Ensure there's only a single CSV header written into the data file #227)
• abort all benchmarks for which the exector is missing (Fast abort of benchmarks when same executable is missing #224)
• make the current invocation accessible in the command as %(invocation)s (Make invocation number accessible #230)

Other changes:

• fix bug where 'None' instead of null was reported to ReBenchDB (Don’t turn extra args into a string if it is None (#215) #232)
• fix handling of environment variables when sudo is used (Fix handling of environment variables when sudo is used. #210)
• try gtime from MacPorts as alternative time command on macOS (Add support for GNU time on macOS #212)
• update py-cpuinfo to work on macOS with ARM-base CPUs (Add support for GNU time on macOS #212)
• make error more readable when executor is not available (Added more readable error when executor is not available #213)
• add testing on macOS on Github Actions (Add testing for ReBench on macOS on GitHub Actions #226)

Thanks to @naomiGrew for the contributions!

[coveralls]

coverage: 83.42%. remained the same when pulling 1286390 on release-1.2.0 into 0e6d009 on master.