Update Examples action to run on Windows, MacOs, and Linux (#974)

Fix windows formatting on PEM encoded certs and add windows tests

---------

Signed-off-by: keastrid <70925169+keastrid@users.noreply.github.com>

Author: keastrid

.github/workflows/examples.yaml

@@ -14,13 +14,23 @@ concurrency:
 
 jobs:
   examples:
-    name: Build and run examples
-    runs-on: ubuntu-latest
+    name: Build and run examples on ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
 
     permissions:
       id-token: write
 
     steps:
+    - name: Enable long paths in Git
+      if: runner.os == 'Windows'
+      run: git config --system core.longpaths true
+      shell: bash
+      
     - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
       with:
         persist-credentials: false
@@ -36,19 +46,22 @@ jobs:
 
     - name: run examples against released sigstore
       working-directory: examples/hello-world
+      shell: bash
       run: ./test.sh
 
     - name: install sigstore java development jars into mavenLocal
       run: ./gradlew publishToMavenLocal -Prelease -PskipSigning
 
     - name: calculate development version
       id: dev_version
+      shell: bash
       run: |
         set -Exeo pipefail
         echo "version=$(grep "^version=" gradle.properties | cut -d'=' -f2)" >> $GITHUB_OUTPUT
 
     - name: run examples against development version
       working-directory: examples/hello-world
+      shell: bash
       env:
         VERSION: ${{ steps.dev_version.outputs.version }}
       run: ./test.sh -Dsigstore.version=${VERSION}

sigstore-java/src/main/java/dev/sigstore/encryption/certificates/Certificates.java

@@ -48,7 +48,7 @@ public static String toPemString(Certificate cert) throws IOException {
       pemWriter.writeObject(cert);
       pemWriter.flush();
     }
-    return certWriter.toString();
+    return certWriter.toString().replaceAll("\r\n", "\n");
   }
 
   /** Convert a certificate to a PEM encoded certificate. */
@@ -94,7 +94,7 @@ public static String toPemString(CertPath certs) throws IOException {
       }
       pemWriter.flush();
     }
-    return certWriter.toString();
+    return certWriter.toString().replaceAll("\r\n", "\n");
   }
 
   /** Convert a CertPath to a PEM encoded certificate chain. */