actions: build-riscv: switch to checkout@v2

Author: jepler

.github/workflows/build.yml

@@ -329,9 +329,14 @@ jobs:
         gcc --version
         riscv64-unknown-elf-gcc --version
         python3 --version
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2
       with:
         submodules: true
+        fetch-depth: 0
+    - run: git fetch --recurse-submodules=no https://github.com/adafruit/circuitpython refs/tags/*:refs/tags/*
+    - run: git submodule sync
+    - run: git submodule foreach git remote -v
+    - run: git submodule foreach git fetch --recurse-submodules=no origin +refs/tags/*:refs/tags/*
     - name: mpy-cross
       run: make -C mpy-cross -j2
     - name: build