CI: install bindgen-cli

`bindgen` is used in our build process to build libtcgtpm.
CI recently started to fail because it was not installed.

Add a step to make sure `bindgen` is installed correctly in our
workflows.

Signed-off-by: Stefano Garzarella <[email protected]>

.github/workflows/rust.yml

@@ -28,6 +28,12 @@ jobs:
             override: true
             components: rustfmt, rust-src, clippy
 
+      - name: Install bindgen-cli
+        uses: actions-rs/cargo@v1
+        with:
+          command: install
+          args: bindgen-cli
+
       - name: Install TPM 2.0 Reference Implementation build dependencies
         run: sudo apt install -y autoconf autoconf-archive pkg-config build-essential automake
 
@@ -143,6 +149,12 @@ jobs:
             override: true
             components: rustfmt, rust-src, clippy
 
+      - name: Install bindgen-cli
+        uses: actions-rs/cargo@v1
+        with:
+          command: install
+          args: bindgen-cli
+
       - name: Install TPM 2.0 Reference Implementation build dependencies
         run: sudo apt install -y autoconf autoconf-archive pkg-config build-essential automake