Update rush pnpm version and adjust version format (#259)

Signed-off-by: Matthew B White <whitemat@uk.ibm.com>

ci/templates/nightly-version-update.yaml

@@ -1,7 +1,7 @@
 steps:
 - script: |
     set -ev 
-    export RELEASE_VERSION=${VERSION}.dev.${DATE_STAMP}
+    export RELEASE_VERSION=${VERSION}-dev-${DATE_STAMP}
     find . \( -wholename "./docs/package.json" -or -wholename "./apis/**/package.json" -or -wholename "./libraries/**/package.json" -or -wholename "./test/**/package.json" \) -exec node ci/updatePackageJson.js {} \;
     node common/scripts/install-run-rush.js update      
   name: UpdateVersionNightlyDrivers

rush.json

@@ -15,7 +15,7 @@
      * path segment in the "$schema" field for all your Rush config files.  This will ensure
      * correct error-underlining and tab-completion for editors such as VS Code.
      */
-     "rushVersion": "5.27.0",
+     "rushVersion": "5.42.0",
     /**
      * The next field selects which package manager should be installed and determines its version.
      * Rush installs its own local copy of the package manager to ensure that your build process
@@ -24,7 +24,7 @@
      * Specify one of: "pnpmVersion", "npmVersion", or "yarnVersion".  See the Rush documentation
      * for details about these alternatives.
      */
-     "pnpmVersion": "4.7.2",
+     "pnpmVersion": "5.18.5",
     /**
      * Options that are only used when the PNPM package manager is selected
      */