Add new Algol68 GCC frontend to the nightly builds

Will be removed when the frontend is merged upstream.

refs compiler-explorer/compiler-explorer#7258

Signed-off-by: Marc Poulhiès <[email protected]>

Author: dkm

compilers.yaml

@@ -7,6 +7,7 @@ compilers:
     - { image: clang, name: llvm, args: llvm-trunk }
     - { image: gcc, name: gcc }
     - { image: gcc, name: gcc_cobol_master, args: cobol-master }
+    - { image: gcc, name: gcc_algol68_master, args: algol68-master }
     - { image: gcc, name: gcc_contracts, args: lock3-contracts-trunk }
     - { image: gcc, name: gcc_contracts_labels, args: lock3-contracts-labels-trunk }
     - { image: gcc, name: gcc_contracts_nonattr, args: contracts-nonattr-trunk }