Support solc v0.8.29 (#261)

No observable changes w.r.t. YUL compilation.
- Mark solc v0.8.29 as the latest supported version
- Add integration test for solc v0.8.29 specific feature
- Use the latest version on CI
- Drive-by fix linter complaints and a two types in the CI yaml files

---------

Signed-off-by: Cyrill Leutwiler <bigcyrill@hotmail.com>
Signed-off-by: xermicus <cyrill@parity.io>

.github/actions/get-solc/action.yml

@@ -1,4 +1,5 @@
 name: "Install Solidity Compiler"
+description: "Installs the Ethereum solc Solidity compiler frontend executable"
 
 runs:
   using: "composite"
@@ -18,7 +19,7 @@ runs:
       shell: bash
       run: |
         mkdir -p solc
-        curl -sSL --output solc/solc https://github.com/ethereum/solidity/releases/download/v0.8.28/${SOLC_NAME}
+        curl -sSL --output solc/solc https://github.com/ethereum/solidity/releases/download/v0.8.29/${SOLC_NAME}
 
     - name: Make Solc Executable
       if: ${{ runner.os == 'Windows' }}