Add spell checking with typos (#4138)

* Add spell checking with typos
Implement https://github.com/FreshRSS/FreshRSS/pull/4134#issuecomment-1008027558

* GitHub Actions attempt

* Quiet wget

* Makefile

.github/workflows/tests.yml

@@ -79,7 +79,7 @@ jobs:
       uses: actions/cache@v2
       with:
         path: bin
-        key: ${{ runner.os }}-bin-shfmt@v3.4.0c-hadolint@v2.7.0
+        key: ${{ runner.os }}-bin-shfmt@v3.4.0c-hadolint@v2.7.0-typos@v1.3.3
 
     - name: Add ./bin/ to $PATH
       run: mkdir -p bin/ && echo "${PWD}/bin" >> $GITHUB_PATH
@@ -106,3 +106,16 @@ jobs:
 
     - name: Check Dockerfile syntax
       run: find . -name 'Dockerfile*' -print0 | xargs -0 -n1 ./bin/hadolint --failure-threshold warning
+
+    - name: Install typos
+      if: steps.shell-cache.outputs.cache-hit != 'true'
+      run: |
+        cd bin ;
+        wget -q 'https://github.com/crate-ci/typos/releases/download/v1.3.3/typos-v1.3.3-x86_64-unknown-linux-musl.tar.gz' &&
+        tar -xvf *.tar.gz './typos' &&
+        chmod +x typos &&
+        rm *.tar.gz ;
+        cd ..
+
+    - name: Check spelling
+      run: bin/typos