Make allow negative keep alive value with OllamaEmbeddingModel

[dev-jonghoonpark]

Motivation:

In issue #2197, it was identified that the keep-alive option for embedding models did not allow negative values. This limitation restricted certain configurations as described in the documentation.

Modification:

Updated the regex to enable the keep-alive option for embedding models to accept negative values.

Result:

Users can now configure negative values for the keep-alive option in embedding models, addressing the issue mentioned.
This resolves #2197.

Verification:

When set to 1m:

The keep-alive duration is correctly set to 1 minute.

Logs:

[GIN] 2025/02/17 - 07:45:12 | 200 |   53.186102ms |   192.168.88.61 | POST     "/api/embed"
time=2025-02-17T07:45:12.956Z level=DEBUG source=sched.go:407 msg="context for request finished"
time=2025-02-17T07:45:12.956Z level=DEBUG source=sched.go:339 msg="runner with non-zero duration has gone idle, adding timer" modelPath=/root/.ollama/models/blobs/sha256-819c2adf5ce6df2b6bd2ae4ca90d2a69f060afeb438d0c171db57daa02e39c3d duration=1m0s

When set to -1m:

The keep-alive duration is correctly interpreted as infinite, as documented.

Logs:

[GIN] 2025/02/17 - 07:40:34 | 200 |   1.04253822s |        10.8.0.3 | POST     "/api/embed"
time=2025-02-17T07:40:34.201Z level=DEBUG source=sched.go:466 msg="context for request finished"
time=2025-02-17T07:40:34.201Z level=DEBUG source=sched.go:339 msg="runner with non-zero duration has gone idle, adding timer" modelPath=/root/.ollama/models/blobs/sha256-819c2adf5ce6df2b6bd2ae4ca90d2a69f060afeb438d0c171db57daa02e39c3d duration=2562047h47m16.854775807s