ci: Add dependabot configuration for monthly updates #307

Job	Run time
Build documentation	55s
Link correctness	5s
Code quality (ty and ruff)	42s
Tests (py3.11, ubuntu-latest, float32, full)	1m 22s
Tests (py3.13, ubuntu-latest, float32, full)	1m 19s
Tests (py3.14, ubuntu-latest, float64, full)	1m 13s
Tests (py3.14, macOS-latest, float32, full)	1m 11s
Tests (py3.10.0, ubuntu-latest, float32, full, lower_bounds)	1m 9s
Tests (py3.14, ubuntu-latest, float32, full)	1m 11s
Tests (py3.12, ubuntu-latest, float32, full)	1m 21s
Tests (py3.14, windows-latest, float32, full)	1m 24s
Tests (py3.14, ubuntu-latest, float32, none)	1m 11s
Tests (py3.10, ubuntu-latest, float32, full)	1m 20s
	14m 23s

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