Update action versions in code examples/templates (#35)

Author: straight-shoota

README.md

@@ -19,10 +19,10 @@ steps:
 
 ```yaml
 steps:
-  - uses: actions/checkout@v3
+  - uses: actions/checkout@v4
   - uses: crystal-lang/install-crystal@v1
     with:
-      crystal: 1.2
+      crystal: 1.11
   - run: shards install
   - run: crystal spec
 ```
@@ -41,7 +41,7 @@ steps:
       - uses: crystal-lang/install-crystal@v1
         with:
           crystal: ${{matrix.crystal}}
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - run: shards install
       - run: crystal spec
       - run: crystal tool format && git diff --exit-code

docs/configurator.md

@@ -85,7 +85,7 @@ jobs:
     {%- endif %}
     steps:
       - name: Download source
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Install Crystal
         uses: crystal-lang/install-crystal@v1
         {%- if crystal_nightly or crystal_ver %}
@@ -94,7 +94,7 @@ jobs:
         {%- endif %}
       {%- if cache_shards %}
       - name: Cache shards
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         with:
           {%- if is_app %}
           path: lib