CompatHelper: bump compat for AdvancedHMC in [weakdeps] to 0.8, (keep existing compat)

[github-actions]

This pull request changes the compat entry for the AdvancedHMC package from 0.6, 0.7 to 0.6, 0.7, 0.8.
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]

JuliaBUGS.jl documentation for PR #319 is available at:
https://TuringLang.github.io/JuliaBUGS.jl/previews/PR319/

[github-actions]

Benchmark results on macOS (aarch64)

BridgeStan not found at location specified by $BRIDGESTAN environment variable, downloading version 2.6.2 to /Users/runner/.bridgestan/bridgestan-2.6.2
Done!

Stan results:

Model	Parameters	Density Time (µs)	Density+Gradient Time (µs)
rats	65	5.3916	7.361
pumps	12	0.806818	1.05668
bones	13	75.792	93.291
oxford	244	10.771	14.208
epil	303	32.833	38.375
lsat	1006	101.542	147.021
schools	133	229.084	394.146
beetles	2	0.779605	0.9014
air	5	0.8345	0.992296

JuliaBUGS Mooncake results:

Model	Parameters	Density Time (µs)	Density+Gradient Time (µs)
rats	65	1.26452	7.8545
pumps	12	0.488517	2.30769
bones	33	55.4795	321.792
oxford	244	19.75	53.375
epil	303	7.83333	43.042
lsat	1006	55.0	245.834
schools	133	116.167	3540.79
beetles	2	0.9639	7.33333
air	5	0.27256	1.29167

---

Benchmark results on Ubuntu (x64)

BridgeStan not found at location specified by $BRIDGESTAN environment variable, downloading version 2.6.2 to /home/runner/.bridgestan/bridgestan-2.6.2
Done!

Stan results:

Model	Parameters	Density Time (µs)	Density+Gradient Time (µs)
rats	65	5.5124	7.64767
pumps	12	0.9658	1.22508
bones	13	73.397	90.128
oxford	244	13.8005	17.8835
epil	303	27.501	34.284
lsat	1006	160.239	198.27
schools	133	495.085	729.643
beetles	2	0.861879	0.998759
air	5	0.663045	0.809583

JuliaBUGS Mooncake results:

Model	Parameters	Density Time (µs)	Density+Gradient Time (µs)
rats	65	1.91753	14.0015
pumps	12	0.596837	2.40192
bones	33	47.4335	359.567
oxford	244	23.744	73.748
epil	303	11.191	55.153
lsat	1006	90.218	361.865
schools	133	103.343	1071.88
beetles	2	1.10631	4.61533
air	5	0.341907	1.36448

[coveralls]

Pull Request Test Coverage Report for Build 15455282714

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 83.518%

---

Totals
Change from base Build 15281006647:	0.0%
Covered Lines:	2108
Relevant Lines:	2524

---

💛 - Coveralls