Merge Gradle wrapper validation job into main pipeline and pin action versions.

Author: charleskorn

.github/workflows/build.yml

@@ -23,18 +23,21 @@ jobs:
           fetch-depth: 0
 
       - name: Cache Batect
-        uses: actions/cache@v2
+        uses: actions/cache@v2.1.7
         with:
           path: ~/.batect/cache
           key: batect-${{ hashFiles('batect') }}
 
       - name: Cache dependencies
-        uses: actions/cache@v2
+        uses: actions/cache@v2.1.7
         id: cache-dependencies
         with:
           path: .batect/caches
           key: batect-caches-${{ hashFiles('**/*.gradle.kts') }}
 
+      - name: Validate Gradle wrapper
+        uses: gradle/wrapper-validation-action@v1.0.4
+
       - name: Build
         run: ./batect build
 
@@ -71,7 +74,7 @@ jobs:
         if: github.repository == 'charleskorn/kaml' && startsWith(github.ref, 'refs/tags/') && github.event_name == 'push'
 
       - name: Create GitHub release
-        uses: softprops/action-gh-release@v1
+        uses: softprops/action-gh-release@v0.1.14
         with:
           files: build/release/*
           fail_on_unmatched_files: true