Add some group parameter to convolutions. (#566)

* Add some group parameter to convolutions.

* Avoid some unnecessary groups checks.

* Move the tensor convolution bits.

* Properh handling of groups.

* Bump the crate version.

* And add a changelog.

candle-examples/examples/yolo-v8/main.rs

@@ -101,7 +101,11 @@ impl ConvBlock {
         padding: Option<usize>,
     ) -> Result<Self> {
         let padding = padding.unwrap_or(k / 2);
-        let cfg = Conv2dConfig { padding, stride };
+        let cfg = Conv2dConfig {
+            padding,
+            stride,
+            groups: 1,
+        };
         let conv = conv2d_no_bias(c1, c2, k, cfg, vb.pp("conv"))?;
         let bn = batch_norm(c2, 1e-3, vb.pp("bn"))?;
         Ok(Self { conv, bn })