chore: bump 'pyo3' to v0.28 (#1847)

https://datadoghq.atlassian.net/browse/PROF-14200

# What does this PR do?

Bumps `pyo3` from `0.27.2` to `0.28` in `datadog-ffe/Cargo.toml`. This is a version
pin change only — the code changes required by the 0.28 API (`type Error` associated
type on `FromPyObject` impls) are already present on main.

# Motivation

`dd-trace-py` links `datadog-ffe` into its native extension (`_native`). Cargo requires
all crates in the dependency graph that link the native `python` library to agree on a
single pyo3 version. With `datadog-ffe` pinned to `0.27.2`, bumping pyo3 in `dd-trace-py`
to `0.28` produces a hard link conflict:

```
error: package pyo3-ffi links to the native library python, but it conflicts
with a previous package which links to python as well: pyo3-ffi v0.27.2
(from datadog-ffe via libdatadog)
```


pyo3 0.28 is the first release with native Python 3.15 support. Until this is resolved,
`dd-trace-py` cannot install on Python 3.15, blocking the profiler's 3.15 CI matrix
and all pytest tests on that version.

# Additional Notes

Migrating `dd-trace-py` (profiling) to Python v3.15: DataDog/dd-trace-py#17294.

# How to test the change?

```bash
$ cd datadog-ffe
$ cargo check --features pyo3
$ cargo test --features pyo3
...
test result: ok. 10 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 1.56s
```

Co-authored-by: vlad.scherbich <vlad.scherbich@datadoghq.com>

Author: vlad-scherbich

Cargo.lock

@@ -203,7 +203,6 @@ idna,https://github.com/servo/rust-url,MIT OR Apache-2.0,The rust-url developers
 idna_adapter,https://github.com/hsivonen/idna_adapter,Apache-2.0 OR MIT,The rust-url developers
 indexmap,https://github.com/bluss/indexmap,Apache-2.0 OR MIT,The indexmap Authors
 indexmap,https://github.com/indexmap-rs/indexmap,Apache-2.0 OR MIT,The indexmap Authors
-indoc,https://github.com/dtolnay/indoc,MIT OR Apache-2.0,David Tolnay <dtolnay@gmail.com>
 io-lifetimes,https://github.com/sunfishcode/io-lifetimes,Apache-2.0 WITH LLVM-exception OR Apache-2.0 OR MIT,Dan Gohman <dev@sunfishcode.online>
 ipconfig,https://github.com/liranringel/ipconfig,MIT OR Apache-2.0,Liran Ringel <liranringel@gmail.com>
 ipnet,https://github.com/krisprice/ipnet,MIT OR Apache-2.0,Kris Price <kris@krisprice.nz>
@@ -467,7 +466,6 @@ unicase,https://github.com/seanmonstar/unicase,MIT OR Apache-2.0,Sean McArthur <
 unicode-ident,https://github.com/dtolnay/unicode-ident,(MIT OR Apache-2.0) AND Unicode-DFS-2016,David Tolnay <dtolnay@gmail.com>
 unicode-width,https://github.com/unicode-rs/unicode-width,MIT OR Apache-2.0,"kwantam <kwantam@gmail.com>, Manish Goregaokar <manishsmail@gmail.com>"
 unicode-xid,https://github.com/unicode-rs/unicode-xid,MIT OR Apache-2.0,"erick.tryzelaar <erick.tryzelaar@gmail.com>, kwantam <kwantam@gmail.com>, Manish Goregaokar <manishsmail@gmail.com>"
-unindent,https://github.com/dtolnay/indoc,MIT OR Apache-2.0,David Tolnay <dtolnay@gmail.com>
 unsafe-libyaml,https://github.com/dtolnay/unsafe-libyaml,MIT,David Tolnay <dtolnay@gmail.com>
 untrusted,https://github.com/briansmith/untrusted,ISC,Brian Smith <brian@briansmith.org>
 url,https://github.com/servo/rust-url,MIT OR Apache-2.0,The rust-url developers

LICENSE-3rdparty.csv

@@ -23,7 +23,7 @@ serde-bool = { version = "0.1.3", default-features = false }
 serde_with = { version = "3.11.0", default-features = false, features = ["base64", "hex", "macros"] }
 thiserror = { version = "2.0.3", default-features = false }
 url = { version = "2.5.0", default-features = false, features = ["std"] }
-pyo3 = { version = "0.27.2", optional = true, default-features = false, features = ["macros"] }
+pyo3 = { version = "0.28", optional = true, default-features = false, features = ["macros"] }
 
 [dev-dependencies]
 env_logger = "0.10"