fix the installation of Rust in the CI (!42)

!39 and !40 changed the CI to use a _toolchain_ file.

however, having `default` as the `$.profile` causes extra useless components to be installed.

this MR sets the `$.profile` to `minimal` in the _toolchain_ file and the `$.components` to `rustfmt` and `clippy`.

.gitlab-ci.yml

@@ -19,8 +19,6 @@ workflow:
 
 fmt:
   stage: fmt
-  before_script:
-    - rustup component add rustfmt
 
   script:
     - make fmt
@@ -34,8 +32,6 @@ test:
     - apt upgrade --yes
     - apt install protobuf-compiler --yes
 
-    - rustup component add clippy
-
     - export NUSHELL_BUILD="nu-$NUSHELL_VERSION-$NUSHELL_ARCH"
     - export PATH="/tmp/:$PATH"
 

rust-toolchain.toml

 [toolchain]
-profile = "default"
+profile = "minimal"
 channel = "1.75"
+components = ["rustfmt", "clippy"]