Only save cache on merge to main (#267)

Author: georgestagg

.github/workflows/R-CMD-check.yaml

@@ -36,6 +36,7 @@ jobs:
         with:
           shared-key: ${{ runner.os }}-R-CMD-Check
           cache-on-failure: true
+          save-if: ${{ github.ref == 'refs/heads/main' }}
 
       - name: Check disk space
         run: df -h

.github/workflows/build.yaml

@@ -40,6 +40,7 @@ jobs:
         with:
           shared-key: ${{ runner.os }}-build
           cache-on-failure: true
+          save-if: ${{ github.ref == 'refs/heads/main' }}
 
       - name: Run Rust formatting check
         run: cargo fmt --all -- --check

.github/workflows/publish.yaml

@@ -41,6 +41,7 @@ jobs:
         with:
           shared-key: ${{ runner.os }}-publish
           cache-on-failure: true
+          save-if: ${{ github.ref == 'refs/heads/main' }}
 
       - name: Install wasm-pack
         run: cargo install wasm-pack

.github/workflows/python.yml

@@ -47,6 +47,7 @@ jobs:
         with:
           shared-key: ${{ matrix.os }}-python
           cache-on-failure: true
+          save-if: ${{ github.ref == 'refs/heads/main' && matrix.python == '3.13' }}
 
       - name: Set up MSVC (Windows)
         if: runner.os == 'Windows'