chore(deps): update transformers requirement

Updates the requirements on [transformers](https://github.com/huggingface/transformers) to permit the latest version.
- [Release notes](https://github.com/huggingface/transformers/releases)
- [Commits](https://github.com/huggingface/transformers/compare/v5.15.0...v5.15.1)

---
updated-dependencies:
- dependency-name: transformers
  dependency-version: 5.15.1
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

backend/python/transformers/requirements-cpu.txt

@@ -2,7 +2,7 @@ torch==2.7.1
 llvmlite==0.43.0
 numba==0.60.0
 accelerate
-transformers>=5.15.0
+transformers>=5.15.1
 bitsandbytes
 sentence-transformers==5.7.0
 diffusers

backend/python/transformers/requirements-cublas12.txt

@@ -2,7 +2,7 @@ torch==2.7.1
 accelerate
 llvmlite==0.43.0
 numba==0.60.0
-transformers>=5.15.0
+transformers>=5.15.1
 bitsandbytes
 sentence-transformers==5.7.0
 diffusers

backend/python/transformers/requirements-cublas13.txt

@@ -2,7 +2,7 @@
 torch==2.9.0
 llvmlite==0.43.0
 numba==0.60.0
-transformers>=5.15.0
+transformers>=5.15.1
 bitsandbytes
 sentence-transformers==5.7.0
 diffusers

backend/python/transformers/requirements-hipblas.txt

@@ -1,7 +1,7 @@
 --extra-index-url https://download.pytorch.org/whl/rocm7.0
 torch==2.10.0+rocm7.0
 accelerate
-transformers>=5.15.0
+transformers>=5.15.1
 llvmlite==0.43.0
 numba==0.60.0
 bitsandbytes

backend/python/transformers/requirements-intel.txt

@@ -3,7 +3,7 @@ torch
 optimum[openvino]
 llvmlite==0.43.0
 numba==0.60.0
-transformers>=5.15.0
+transformers>=5.15.1
 bitsandbytes
 sentence-transformers==5.7.0
 diffusers

backend/python/transformers/requirements-mps.txt

@@ -2,7 +2,7 @@ torch==2.7.1
 llvmlite==0.43.0
 numba==0.60.0
 accelerate
-transformers>=5.15.0
+transformers>=5.15.1
 bitsandbytes
 sentence-transformers==5.7.0
 diffusers