Include function to get cfitsio version

[simonrw]

We provide an example to print the cfitiso version.

Note: this is designed to work on versions 3+ so we don't support the semver patch version (yet).

We also add running this example before each test that uses features so that we can debug in the future cfitsio versions.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 12 lines in your changes missing coverage. Please review.

Project coverage is 89.0%. Comparing base (f306c58) to head (1001232).

Files with missing lines	Patch %	Lines
fitsio-sys/src/lib.rs	0.0%	12 Missing ⚠️

Additional details and impacted files

Files with missing lines	Coverage Δ
fitsio-sys/src/lib.rs	0.0% <0.0%> (ø)