ci: Take the new next branch into account

.github/workflows/docs.yml

@@ -2,7 +2,7 @@ name: Documentation
 
 on:
   push:
-    branches: [main]
+    branches: [next]
 
 jobs:
   build-deploy:

.github/workflows/msrv.yml

@@ -2,9 +2,9 @@ name: Rust 1.45
 
 on:
   push:
-    branches: [main]
+    branches: [main, next]
   pull_request:
-    branches: [main]
+    branches: [main, next]
 
 jobs:
   check_msrv:

.github/workflows/nightly.yml

@@ -2,9 +2,9 @@ name: Rust Nightly
 
 on:
   push:
-    branches: [main]
+    branches: [main, next]
   pull_request:
-    branches: [main]
+    branches: [main, next]
 
 jobs:
   check_nightly:

.github/workflows/stable.yml

@@ -2,9 +2,9 @@ name: Rust Stable
 
 on:
   push:
-    branches: [main]
+    branches: [main, next]
   pull_request:
-    branches: [main]
+    branches: [main, next]
 
 jobs:
   check_stable: