Add wgpu option

Cargo.toml

@@ -5,13 +5,26 @@ edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
+[features]
+default = ["torch-backend"]
+torch-backend = ["burn-tch"]
+wgpu-backend = ["burn-wgpu"]
+
+[dependencies.burn-tch]
+version = "0.8.0"
+optional = true
+
+[dependencies.burn-wgpu]
+version = "0.8.0"
+optional = true
+
 [dependencies]
 burn = "0.8.0"
-burn-tch = "0.8.0"
 serde = {version = "1.0.171", features = ["std", "derive"]}
 npy = "0.4.0"
 num-traits = "0.2.15"
 rust_tokenizers = "8.1.0"
 regex = "1.9.1"
 image = "0.24.6"
-bincode = {version = "2.0.0-alpha.0", features = ["std"]}
+bincode = {version = "2.0.0-alpha.0", features = ["std"]}
+cfg-if = "0.1"