Update nanobind requirement from <2.8.0 to <2.9.0

[dependabot]

Updates the requirements on nanobind to permit the latest version.

Changelog

Sourced from nanobind's changelog.

Version 2.8.0 (July 16, 2025)

• Added :cpp:class:nb::fallback <fallback> wrapper type, which is a :cpp:class:nb::handle <handle> that always requires implicit conversion during casting. This is convenient when adding catch-all overloads that must handle arbitrary Python objects, without interfering with implicit conversion of arguments in other overloads.

• The nanobind::literals namespace now includes _s to create a Python string from source code literals. (PR [#1051](https://github.com/wjakob/nanobind/issues/1051) <https://github.com/wjakob/nanobind/pull/1051>__).

• Added :cpp:func:nb::dict::empty() <dict::empty>, :cpp:func:nb::list::empty() <list::empty>, :cpp:func:nb::set::empty() <set::empty>, and :cpp:func:nb::tuple::empty() <tuple::empty> convenience methods. (PR [#1052](https://github.com/wjakob/nanobind/issues/1052) <https://github.com/wjakob/nanobind/pull/1052>__)

• Added a :cpp:func:nb::dict::get() <dict::get> function to perform dictionary lookups with a fallback value in case of failures. (commit d38284 <https://github.com/wjakob/nanobind/commit/d38284e573e404503862a550804e4c2413e11e01>__).

• Nanobind now uses multi-phase (as opposed to single-phase) initialization API when registering modules. However, multi-interpreter extensions remain unsupported. (PR [#1059](https://github.com/wjakob/nanobind/issues/1059) <https://github.com/wjakob/nanobind/pull/1059>__).

• Added :cpp:class:nb::frozenset that wraps the Python frozenset type. (PR [#1068](https://github.com/wjakob/nanobind/issues/1068) <https://github.com/wjakob/nanobind/pull/1068>__)

• Miscellaneous fixes and improvements ( commits d4b245 <https://github.com/wjakob/nanobind/commit/d4b245ad69f729c3d2095be4c1cb5b94810dae26>, 667451 <https://github.com/wjakob/nanobind/commit/667451fb4566dcd7151d64d81e118f9ba194a889>, 62fc99 <https://github.com/wjakob/nanobind/commit/62fc996018d9ea4d51af9c86cf008c2562b4eeab>, 8497f7 <https://github.com/wjakob/nanobind/commit/8497f778d006b60e44e99530f241e22f9603bb04>).

Version 2.7.0 (Apr 18, 2025)

• nanobind now provides a zero-copy type caster for Eigen::Map<Eigen::SparseMatrix>. (PRs [#1003](https://github.com/wjakob/nanobind/issues/1003) <https://github.com/wjakob/nanobind/pull/1003>, [#782](https://github.com/wjakob/nanobind/issues/782) <https://github.com/wjakob/nanobind/pull/782>).

• Made handling of return value policies in Eigen type casters more consistent with the rest of nanobind. (Issue [#971](https://github.com/wjakob/nanobind/issues/971) <https://github.com/wjakob/nanobind/issues/971>, commit 5cdf59 <https://github.com/wjakob/nanobind/commit/5cdf58984e7a8b520935c3771029fe0e87edee73>).

• The Eigen sparse matrix caster now correctly handles scipy.sparse objects

... (truncated)

Commits

• 0e7aa61 v2.8.0 release
• 8497f77 make nb::implicitly_convertible() a no-op if Source==Target
• fc08a19 gitignore: add .pyi files
• a0ed258 SciPy test fixes
• d38284e Added nb::dict::get() function with fallback value
• a787cca Remove argument from Cmake else() command (#1081)
• f4f546b another fix for the sanitizer detection code..
• 66e0e2d expand macros in new multi-phase initialization code
• d0b9ea6 small tweak to stub sanitizer detection code
• 80c37ed Added nb::fallback wrapper type
• Additional commits viewable in compare view

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Test Results

8 tests  ±0   8 ✅ ±0   12s ⏱️ -2s
1 suites ±0   0 💤 ±0 
1 files   ±0   0 ❌ ±0 

Results for commit 3cd247f. ± Comparison against base commit 3f788fa.