ci: pin 3rd party action dependencies, setup dependabot (#147)

as suggested in #146. and one more readme fix noted in #133

Author: wpbonelli

.github/dependabot.yml

@@ -0,0 +1,7 @@
+# https://docs.github.com/github/administering-a-repository/configuration-options-for-dependency-updates
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/" # Location of package manifests
+    schedule:
+      interval: "daily"

README.md

@@ -40,6 +40,8 @@ jobs:
         exclude:
           - os: macos-latest
             toolchain: {compiler: intel}
+          - os: macos-latest
+            toolchain: {compiler: intel-classic}
           - os: macos-latest
             toolchain: {compiler: nvidia-hpc}
           - os: windows-latest

action.yml

@@ -58,7 +58,7 @@ runs:
         else
           echo "install=true" >> $GITHUB_OUTPUT
         fi
-    - uses: mamba-org/setup-micromamba@v1
+    - uses: mamba-org/setup-micromamba@v2.0.6
       if: runner.os == 'macOS' && contains(inputs.compiler, 'lfortran') && steps.check-umamba.outputs.install == 'true'
       with:
         init-shell: bash
@@ -140,4 +140,4 @@ runs:
 
     - name: Setup MSVC toolchain (Windows)
       if: runner.os == 'Windows' && contains(inputs.compiler, 'lfortran')
-      uses: ilammy/msvc-dev-cmd@v1
+      uses: ilammy/msvc-dev-cmd@v1.13.0