CI: Create cache-bin when downloading gcc

Author: adamgreig

.github/workflows/ci.yaml

@@ -61,7 +61,7 @@ jobs:
       - name: Install arm-none-eabi-gcc and qemu
         if: steps.cache-bin.outputs.cache-hit != 'true'
         run: |
-          mkdir gcc
+          mkdir -p gcc ~/cache-bin
           curl -L https://developer.arm.com/-/media/Files/downloads/gnu-rm/7-2018q2/gcc-arm-none-eabi-7-2018-q2-update-linux.tar.bz2?revision=bc2c96c0-14b5-4bb4-9f18-bceb4050fee7?product=GNU%20Arm%20Embedded%20Toolchain,64-bit,,Linux,7-2018-q2-update \
             | tar --strip-components=1 -C gcc -xj
           cp gcc/bin/* ~/cache-bin
@@ -73,7 +73,6 @@ jobs:
       - name: Copy installed binaries to cache directory
         if: steps.cache-bin.outputs.cache-hit != 'true'
         run: |
-          mkdir ~/cache-bin
           cp ~/.cargo/bin/* ~/cache-bin
 
       - name: Put new bin directory into path