Fix writing FITS in fileinfo for unicode

[maxnoe]

No description provided.

[codecov]

Codecov Report

Merging #1789 (e19e95f) into master (63e0df4) will decrease coverage by 0.01%.
The diff coverage is 42.85%.

@@            Coverage Diff             @@
##           master    #1789      +/-   ##
==========================================
- Coverage   91.80%   91.79%   -0.02%     
==========================================
  Files         188      188              
  Lines       14910    14914       +4     
==========================================
+ Hits        13688    13690       +2     
- Misses       1222     1224       +2     

Impacted Files	Coverage Δ
ctapipe/conftest.py	95.41% <ø> (ø)
ctapipe/tools/fileinfo.py	17.64% <0.00%> (-0.73%)	⬇️
ctapipe/tools/tests/test_tools.py	100.00% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 63e0df4...e19e95f. Read the comment docs.