Remove changelog

[TGWDB]

Remove the CHANGELOG file since it is not maintained/updated since CBMC version 5.9

• Each commit message has a non-empty body, explaining why the change was made.
• Methods or procedures I have added are documented, following the guidelines provided in CODING_STANDARD.md.
• The feature or user visible behaviour I have added or modified has been documented in the User Guide in doc/cprover-manual/
• Regression or unit tests are included, or existing tests cover the modified code (in this case I have detailed which ones those are in the commit message).
• My commit message includes data points confirming performance improvements (if claimed).
• My PR is restricted to a single feature or bugfix.
• White-space or formatting changes outside the feature-related changed lines are in commits of their own.

[tautschnig]

Sad to see this go.

[codecov]

Codecov Report

Merging #6019 (cacf817) into develop (74fbfba) will decrease coverage by 0.09%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop    #6019      +/-   ##
===========================================
- Coverage    74.23%   74.13%   -0.10%     
===========================================
  Files         1444     1444              
  Lines       157328   157322       -6     
===========================================
- Hits        116785   116637     -148     
- Misses       40543    40685     +142     

Impacted Files	Coverage Δ
src/solvers/flattening/boolbv.cpp	79.27% <ø> (+2.46%)	⬆️
src/solvers/smt2/smt2_conv.cpp	60.07% <ø> (+0.12%)	⬆️
src/goto-programs/read_goto_binary.cpp	30.84% <0.00%> (-16.83%)	⬇️
src/ansi-c/c_typecheck_type.cpp	62.96% <0.00%> (-13.43%)	⬇️
src/util/mp_arith.cpp	41.55% <0.00%> (-9.10%)	⬇️
src/util/std_types.cpp	83.95% <0.00%> (-4.94%)	⬇️
src/linking/static_lifetime_init.cpp	95.89% <0.00%> (-2.74%)	⬇️
src/util/json_irep.cpp	92.85% <0.00%> (-1.79%)	⬇️
src/util/unicode.cpp	80.91% <0.00%> (-1.53%)	⬇️
src/util/expr.cpp	74.26% <0.00%> (-1.48%)	⬇️
... and 2 more

---

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 366989f...cacf817. Read the comment docs.

[martin-cs]

RIP 🪦