Fixed missed node version updates (#15099)

The TPN update workflow has been failing for a while. It appears to be
related to the node version, so I updated the remaining occurrences of
Node.js 18 to 20 to match the rest.
###### Microsoft Reviewers: [Open in
CodeFlow](https://microsoft.github.io/open-pr/?codeflow=https://github.com/Azure/bicep/pull/15099)

.github/workflows/codeql.yml

@@ -38,7 +38,7 @@ jobs:
       - name: Setup Node.js
         uses: actions/setup-node@v4
         with:
-          node-version: 18
+          node-version: 20
 
       - name: Build All Projects
         run: |
@@ -60,4 +60,4 @@ jobs:
           npm --prefix src/monarch run build
 
       - name: Perform CodeQL Analysis
-        uses: github/codeql-action/analyze@v3
+        uses: github/codeql-action/analyze@v3

.github/workflows/github-pages.yml

@@ -30,7 +30,7 @@ jobs:
       - name: Setup Node.js
         uses: actions/setup-node@v4
         with:
-          node-version: 18
+          node-version: 20
 
       - name: npm ci
         run: npm ci
@@ -65,4 +65,4 @@ jobs:
     steps:
       - name: Deploy
         id: deployment
-        uses: actions/deploy-pages@v4
+        uses: actions/deploy-pages@v4

.github/workflows/update-notices.yml

@@ -34,7 +34,7 @@ jobs:
       - name: Setup Node.js
         uses: actions/setup-node@v4
         with:
-          node-version: 18
+          node-version: 20
 
       - name: Add msbuild to PATH
         uses: microsoft/setup-msbuild@v2
@@ -47,14 +47,14 @@ jobs:
 
       - name: Publish Language Server
         run: dotnet publish --configuration Release ./src/Bicep.LangServer/Bicep.LangServer.csproj
-      
+
       # this command is not correct for releasing the binaries but is sufficient for the purposes of this job
       - name: Windows Installer prerequisites
         run: mkdir ./src/installer-win/bicep && copy ./src/Bicep.Cli/obj/project.assets.json ./src/installer-win/bicep/ && copy ./src/Bicep.Cli/bin/Release/net8.0/bicep.* ./src/installer-win/bicep/
 
       - name: Build Windows Installer
         run: dotnet build --configuration Release ./src/installer-win/installer.proj
-      
+
       - name: CLI Package prerequisites
         run:  mkdir ./src/Bicep.Cli.Nuget/tools && copy ./src/Bicep.Cli/obj/project.assets.json ./src/Bicep.Cli.Nuget/tools/ && copy ./src/Bicep.Cli/bin/Release/net8.0/bicep.* ./src/Bicep.Cli.Nuget/tools/