Add dependabot to auto-update submodules

.github/dependabot.yml

@@ -0,0 +1,67 @@
+version: 2
+
+updates:
+  # submit a PR for bumping submodules daily (for selected submodules).
+  # updates a submodule to the latest commit on the branch given in .gitmodules.
+  # if branch not given, then it defaults to the main/master branch.
+  - package-ecosystem: gitsubmodule
+    schedule:
+      interval: "daily"
+    directory: /
+    # select submodules
+    allow:
+      - dependency-name: "fpga/fpga-shells"
+      - dependency-name: "generators/bar-fetchers"
+      - dependency-name: "generators/boom"
+      - dependency-name: "generators/caliptra-aes-acc"
+      - dependency-name: "generators/constellation"
+      - dependency-name: "generators/cva6"
+      - dependency-name: "generators/diplomacy"
+      - dependency-name: "generators/fft-generator"
+      #- dependency-name: "generators/gemmini"
+      - dependency-name: "generators/hardfloat"
+      - dependency-name: "generators/ibex"
+      - dependency-name: "generators/icenet"
+      - dependency-name: "generators/mempress"
+      - dependency-name: "generators/nvdla"
+      - dependency-name: "generators/riscv-sodor"
+      - dependency-name: "generators/rocc-acc-utils"
+      #- dependency-name: "generators/rocket-chip"
+      #- dependency-name: "generators/rocket-chip-blocks"
+      #- dependency-name: "generators/rocket-chip-inclusive-cache"
+      - dependency-name: "generators/shuttle"
+      - dependency-name: "generators/testchipip"
+      - dependency-name: "generators/rerocc"
+      - dependency-name: "generators/compress-acc"
+
+      - dependency-name: "sims/firesim"
+
+      - dependency-name: "software/baremetal-ide"
+      - dependency-name: "software/coremark"
+      - dependency-name: "software/embench/embench-iot"
+      - dependency-name: "software/firemarshal"
+      - dependency-name: "software/nvdla-workload"
+      - dependency-name: "software/spec2017"
+
+      - dependency-name: "toolchains/libgloss"
+      - dependency-name: "toolchains/riscv-tools/riscv-isa-sim"
+      - dependency-name: "toolchains/riscv-tools/riscv-openocd"
+      - dependency-name: "toolchains/riscv-tools/riscv-pk"
+      - dependency-name: "toolchains/riscv-tools/riscv-spike-devices"
+      #- dependency-name: "toolchains/riscv-tools/riscv-tests"
+      #- dependency-name: "toolchains/riscv-tools/riscv-tools-feedstock"
+
+      - dependency-name: "tools/DRAMSim2"
+      - dependency-name: "tools/axe"
+      - dependency-name: "tools/cde"
+      - dependency-name: "tools/circt"
+      - dependency-name: "tools/dsptools-fixedpoint"
+      - dependency-name: "tools/fixedpoint-chisel3"
+      - dependency-name: "tools/install-circt"
+      - dependency-name: "tools/rocket-dsp-utils"
+      - dependency-name: "tools/torture"
+      - dependency-name: "tools/dsptools"
+      - dependency-name: "tools/fixedpoint"
+      - dependency-name: "tools/midas-targetutils"
+
+      - dependency-name: "vlsi/hammer-mentor-plugins"