Fix testing mdbook (#465)

Signed-off-by: Moritz Hoffmann <antiguru@gmail.com>

.github/workflows/test.yml

@@ -1,6 +1,8 @@
 name: "Test Suite"
 on:
   push:
+    branches:
+      - master
   pull_request:
 
 jobs:
@@ -30,14 +32,12 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      # Ensure rustfmt is installed and setup problem matcher
       - uses: actions-rust-lang/setup-rust-toolchain@v1
-        with:
-          components: rustfmt
-      - run: cargo build
-      - name: test mdBook
         # rustdoc doesn't build dependencies, so it needs to run after `cargo build`,
         # but its dependency search gets confused if there are multiple copies of any
         # dependency in target/debug/deps, so it needs to run before `cargo test` et al.
         # clutter target/debug/deps with multiple copies of things.
+      - run: cargo clean
+      - run: cargo build
+      - name: test mdBook
         run: for file in $(find mdbook -name '*.md' | sort); do rustdoc --test $file  -L ./target/debug/deps; done