Separate build and install targets

Author: hoop33

Makefile

@@ -1,5 +1,8 @@
-install:
+build:
 	cargo build --release
+install: build
 	sudo cp target/release/onefetch /usr/local/bin
 uninstall:
 	sudo rm -f /usr/local/bin/onefetch
+clean:
+	cargo clean