Adds upgrade notice. (#819)

Author: LeFnord

.github/workflows/ruby.yml

@@ -15,7 +15,7 @@ jobs:
       matrix:
         ruby-version: ['2.6', '2.7', '3.0']
         grape-version: [1.5.2, 1.4.0, 1.3.3]
-        model-parser: [grape-swagger-entity, grape-swagger-representable]
+        model-parser: [grape-swagger-entity, grape-swagger-representable, '']
 
     steps:
     - uses: actions/checkout@v2

CHANGELOG.md

@@ -3,7 +3,9 @@
 #### Features
 
 * Your contribution here.
- * [#815](https://github.com/ruby-grape/grape-swagger/pull/815): Add required for multiple presents - [@MaximeRDY](https://github.com/MaximeRDY).
+
+* [#818](https://github.com/ruby-grape/grape-swagger/pull/818): Adds ruby 3.0 support - [@LeFnord](https://github.com/LeFnord).
+* [#815](https://github.com/ruby-grape/grape-swagger/pull/815): Add required for multiple presents - [@MaximeRDY](https://github.com/MaximeRDY).
 
 #### Fixes
 

UPGRADING.md

@@ -1,5 +1,9 @@
 ## Upgrading Grape-swagger
 
+### Upgrading to >= 1.4.0
+
+- Official support for ruby < 2.5 removed, ruby 2.5 only in testing mode, but no support.
+
 ### Upgrading to >= 1.3.0
 
 - The model (entity) description no longer comes from the route description. It will have a default value: `<<EntityName>> model`.