Remove DataStructures docs dep

[penelopeysm]

Not used anywhere so I think it should be OK to remove it.

Replacement of #1006.

[github-actions]

Benchmark Report for Commit 7088e43

Computer Information

Julia Version 1.11.6
Commit 9615af0f269 (2025-07-09 12:58 UTC)
Build Info:
  Official https://julialang.org/ release
Platform Info:
  OS: Linux (x86_64-linux-gnu)
  CPU: 4 × AMD EPYC 7763 64-Core Processor
  WORD_SIZE: 64
  LLVM: libLLVM-16.0.6 (ORCJIT, znver3)
Threads: 1 default, 0 interactive, 1 GC (on 4 virtual cores)

Benchmark Results

|                 Model | Dimension |  AD Backend |      VarInfo Type | Linked | Eval Time / Ref Time | AD Time / Eval Time |
|-----------------------|-----------|-------------|-------------------|--------|----------------------|---------------------|
| Simple assume observe |         1 | forwarddiff |             typed |  false |                  9.6 |                 1.6 |
|           Smorgasbord |       201 | forwarddiff |             typed |  false |                748.1 |                37.6 |
|           Smorgasbord |       201 | forwarddiff | simple_namedtuple |   true |                421.8 |                55.6 |
|           Smorgasbord |       201 | forwarddiff |           untyped |   true |               1233.1 |                28.6 |
|           Smorgasbord |       201 | forwarddiff |       simple_dict |   true |               3532.7 |                23.3 |
|           Smorgasbord |       201 | reversediff |             typed |   true |               1496.7 |                28.5 |
|           Smorgasbord |       201 |    mooncake |             typed |   true |                987.3 |                 5.0 |
|    Loop univariate 1k |      1000 |    mooncake |             typed |   true |               5614.4 |                 4.0 |
|       Multivariate 1k |      1000 |    mooncake |             typed |   true |               1023.8 |                 8.8 |
|   Loop univariate 10k |     10000 |    mooncake |             typed |   true |              61919.1 |                 3.6 |
|      Multivariate 10k |     10000 |    mooncake |             typed |   true |               8586.2 |                10.0 |
|               Dynamic |        10 |    mooncake |             typed |   true |                129.5 |                12.0 |
|              Submodel |         1 |    mooncake |             typed |   true |                 13.7 |                 6.6 |
|                   LDA |        12 | reversediff |             typed |   true |                462.1 |                 6.0 |

[penelopeysm]

Docs built fine, will queue to merge

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.72%. Comparing base (ce7c8b1) to head (7088e43).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1007      +/-   ##
==========================================
- Coverage   82.97%   82.72%   -0.26%     
==========================================
  Files          36       36              
  Lines        3965     3965              
==========================================
- Hits         3290     3280      -10     
- Misses        675      685      +10     

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