CompatHelper: bump compat for AbstractPPL to 0.9, (keep existing compat)

[github-actions]

This pull request changes the compat entry for the AbstractPPL package from 0.8.4 to 0.8.4, 0.9.
This keeps the compat entries for earlier versions.

Note: I have not tested your package with this new compat entry.
It is your responsibility to make sure that your package tests pass before you merge this pull request.

[github-actions]

BridgeStan not found at location specified by $BRIDGESTAN environment variable, downloading version 2.5.0 to /home/runner/.bridgestan/bridgestan-2.5.0
Done!
Model dogs produces error: ErrorException("log_density() failed with exception: Exception: bernoulli_lpmf: Probability parameter is inf, but must be in the interval [0, 1] (in '/home/runner/work/JuliaBUGS.jl/JuliaBUGS.jl/benchmark/stan/bugs_examples/vol1/dogs/dogs.stan', line 37, column 6 to line 38, column 62)\n")

Model	Parameter Count	Data Count	Stan Density Time (µs)	Stan Density Gradient Time (µs)	JuliaBUGS Density Time with Graph Walk (µs)	JuliaBUGS Density Gradient Time with ReverseDiff.jl(compiled tape) (µs)
rats	65	150	5.5324	8.182	7075.39	118.161
pumps	12	10	1.01531	1.3325	179.626	6.695
dogs	2	720	NA	NA	3626.69	153.197
seeds	26	21	2.51918	3.15822	652.391	20.95
surgical_realistic	14	12	1.27413	1.60639	235.05	8.87
magnesium	108	96	10.63	12.203	9335.89	82.765
salm	22	18	2.42783	3.04789	485.094	13.24
equiv	15	20	2.48133	3.494	365.916	16.12
dyes	9	30	1.0049	1.34114	243.085	13.2995
stacks	6	21	1.13212	1.67612	310.261	15.459
epil	303	236	34.614	39.044	64297.2	284.563
blockers	47	44	3.28167	3.74271	2014.88	32.11
oxford	244	240	16.52	19.116	47317.8	195.036
lsat	1006	5000	179.421	221.93	2.97943e6	1989.4
bones	33	422	72.777	89.998	14110.3	199.739
mice	20	65	7.27625	9.46767	1042.8	39.314
kidney	64	58	10.9255	16.351	3660.45	80.776
leuk	18	714	20.468	26.661	10235.4	218.554
leukfr	40	714	23.735	31.91	19010.1	278.702

[coveralls]

Pull Request Test Coverage Report for Build 11494113489

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 77.678%

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Totals
Change from base Build 11494108749:	0.0%
Covered Lines:	1378
Relevant Lines:	1774

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