Remove assert on downcast, fixing a panic

[edg-l]

Fixes #821

Apparently in cairo you can downcast a smaller type into a bigger type (even both being non bounded ints), the code was already in place to handle this conversion (only needed to remove a unreachable and handle that path, i added a comment there).

Checklist

• Linked to Github Issue
• Unit tests added
• Integration tests added.
• This change requires new documentation.
  • Documentation has been added/updated.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 38.82353% with 52 lines in your changes missing coverage. Please review.

Project coverage is 87.98%. Comparing base (ae17dd3) to head (374734f).

Files with missing lines	Patch %	Lines
src/libfuncs/cast.rs	38.82%	52 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #822      +/-   ##
==========================================
- Coverage   88.03%   87.98%   -0.06%     
==========================================
  Files         122      122              
  Lines       34270    34289      +19     
==========================================
- Hits        30171    30169       -2     
- Misses       4099     4120      +21     

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Benchmark results Main vs HEAD

Command	Mean [s]	Min [s]	Max [s]	Relative
head factorial_2M.cairo (JIT)	3.185 ± 0.024	3.130	3.214	1.01 ± 0.02
base factorial_2M.cairo (JIT)	3.167 ± 0.056	3.088	3.272	1.00
head factorial_2M.cairo (AOT)	3.200 ± 0.038	3.144	3.251	1.01 ± 0.02
base factorial_2M.cairo (AOT)	3.185 ± 0.031	3.145	3.223	1.01 ± 0.02

Command	Mean [s]	Min [s]	Max [s]	Relative
head fib_2M.cairo (JIT)	2.730 ± 0.021	2.692	2.768	1.01 ± 0.02
base fib_2M.cairo (JIT)	2.730 ± 0.025	2.699	2.771	1.01 ± 0.02
head fib_2M.cairo (AOT)	2.715 ± 0.038	2.652	2.754	1.00
base fib_2M.cairo (AOT)	2.733 ± 0.025	2.688	2.773	1.01 ± 0.02

Command	Mean [s]	Min [s]	Max [s]	Relative
head logistic_map.cairo (JIT)	3.162 ± 0.033	3.122	3.215	1.05 ± 0.02
base logistic_map.cairo (JIT)	3.254 ± 0.041	3.203	3.325	1.08 ± 0.02
head logistic_map.cairo (AOT)	3.023 ± 0.045	2.946	3.080	1.00
base logistic_map.cairo (AOT)	3.044 ± 0.037	2.990	3.110	1.01 ± 0.02

[github-actions]

Benchmark results Main vs HEAD

Command	Mean [s]	Min [s]	Max [s]	Relative
head factorial_2M.cairo (JIT)	3.073 ± 0.014	3.047	3.097	1.00 ± 0.01
base factorial_2M.cairo (JIT)	3.090 ± 0.021	3.057	3.117	1.01 ± 0.01
head factorial_2M.cairo (AOT)	3.080 ± 0.017	3.060	3.118	1.00 ± 0.01
base factorial_2M.cairo (AOT)	3.066 ± 0.012	3.041	3.083	1.00

Command	Mean [s]	Min [s]	Max [s]	Relative
head fib_2M.cairo (JIT)	2.620 ± 0.024	2.580	2.672	1.00
base fib_2M.cairo (JIT)	2.646 ± 0.013	2.627	2.663	1.01 ± 0.01
head fib_2M.cairo (AOT)	2.628 ± 0.018	2.599	2.653	1.00 ± 0.01
base fib_2M.cairo (AOT)	2.632 ± 0.015	2.598	2.654	1.00 ± 0.01

Command	Mean [s]	Min [s]	Max [s]	Relative
head logistic_map.cairo (JIT)	3.032 ± 0.010	3.014	3.046	1.05 ± 0.01
base logistic_map.cairo (JIT)	3.045 ± 0.010	3.026	3.062	1.05 ± 0.01
head logistic_map.cairo (AOT)	2.893 ± 0.011	2.870	2.904	1.00
base logistic_map.cairo (AOT)	2.896 ± 0.016	2.876	2.928	1.00 ± 0.01

[github-actions]

Benchmark results Main vs HEAD

Command	Mean [s]	Min [s]	Max [s]	Relative
head factorial_2M.cairo (JIT)	3.157 ± 0.022	3.123	3.184	1.01 ± 0.01
base factorial_2M.cairo (JIT)	3.134 ± 0.026	3.091	3.164	1.00
head factorial_2M.cairo (AOT)	3.142 ± 0.026	3.092	3.182	1.00 ± 0.01
base factorial_2M.cairo (AOT)	3.152 ± 0.021	3.105	3.176	1.01 ± 0.01

Command	Mean [s]	Min [s]	Max [s]	Relative
head fib_2M.cairo (JIT)	2.748 ± 0.025	2.707	2.789	1.02 ± 0.01
base fib_2M.cairo (JIT)	2.727 ± 0.030	2.672	2.757	1.01 ± 0.01
head fib_2M.cairo (AOT)	2.747 ± 0.031	2.700	2.791	1.02 ± 0.01
base fib_2M.cairo (AOT)	2.700 ± 0.021	2.666	2.731	1.00

Command	Mean [s]	Min [s]	Max [s]	Relative
head logistic_map.cairo (JIT)	3.122 ± 0.018	3.087	3.147	1.06 ± 0.01
base logistic_map.cairo (JIT)	3.100 ± 0.030	3.046	3.149	1.05 ± 0.01
head logistic_map.cairo (AOT)	2.958 ± 0.020	2.929	3.003	1.00 ± 0.01
base logistic_map.cairo (AOT)	2.947 ± 0.009	2.933	2.958	1.00