Bump gitreleasemanager.tool from 0.15.0 to 0.20.0

Bumps [gitreleasemanager.tool](https://github.com/GitTools/GitReleaseManager) from 0.15.0 to 0.20.0.
---
updated-dependencies:
- dependency-name: gitreleasemanager.tool
  dependency-type: direct:development
  update-type: version-update:minor
...

Signed-off-by: dotnet-updater[bot] <100138291+dotnet-updater[bot]@users.noreply.github.com>

Author: dotnet-updater[bot]

.config/dotnet-tools.json

@@ -6,31 +6,36 @@
       "version": "6.0.0",
       "commands": [
         "coverlet"
-      ]
+      ],
+      "rollForward": false
     },
     "jetbrains.resharper.globaltools": {
       "version": "2023.2.2",
       "commands": [
         "jb"
-      ]
+      ],
+      "rollForward": false
     },
     "dotnet-ef": {
       "version": "7.0.11",
       "commands": [
         "dotnet-ef"
-      ]
+      ],
+      "rollForward": false
     },
     "gitversion.tool": {
       "version": "5.12.0",
       "commands": [
         "dotnet-gitversion"
-      ]
+      ],
+      "rollForward": false
     },
     "gitreleasemanager.tool": {
-      "version": "0.15.0",
+      "version": "0.20.0",
       "commands": [
         "dotnet-gitreleasemanager"
-      ]
+      ],
+      "rollForward": false
     }
   }
 }