Add function that prints Hecke banner

[paemurru]

No description provided.

[codecov]

Codecov Report

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

Project coverage is 75.80%. Comparing base (137e629) to head (f630559).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
src/Hecke.jl	0.00%	12 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1641      +/-   ##
==========================================
- Coverage   75.80%   75.80%   -0.01%     
==========================================
  Files         361      361              
  Lines      113700   113701       +1     
==========================================
- Hits        86192    86188       -4     
- Misses      27508    27513       +5     

Files with missing lines	Coverage Δ
src/Hecke.jl	51.94% <0.00%> (-0.34%)	⬇️

... and 30 files with indirect coverage changes