Adjust the build workflow's cache key formatting

This will return the cache key to being a string with no new lines.

Author: mcdonnnj

.github/workflows/build.yml

@@ -120,16 +120,18 @@ jobs:
           echo "dir=$(go env GOCACHE)" >> $GITHUB_OUTPUT
       - uses: actions/cache@v4
         env:
-          BASE_CACHE_KEY: ${{ github.job }}-${{ runner.os }}-\
-            py${{ steps.setup-python.outputs.python-version }}-\
-            go${{ steps.setup-go.outputs.go-version }}-\
-            packer${{ steps.setup-env.outputs.packer-version }}-\
-            tf${{ steps.setup-env.outputs.terraform-version }}-
+          BASE_CACHE_KEY: >-
+            ${{ github.job }}-${{ runner.os
+            }}-py${{ steps.setup-python.outputs.python-version
+            }}-go${{ steps.setup-go.outputs.go-version
+            }}-packer${{ steps.setup-env.outputs.packer-version
+            }}-tf${{ steps.setup-env.outputs.terraform-version }}-
         with:
-          key: ${{ env.BASE_CACHE_KEY }}\
-            ${{ hashFiles('**/requirements-test.txt') }}-\
-            ${{ hashFiles('**/requirements.txt') }}-\
-            ${{ hashFiles('**/.pre-commit-config.yaml') }}
+          key: >-
+            ${{ env.BASE_CACHE_KEY }}${{
+            hashFiles('**/requirements-test.txt') }}-${{
+            hashFiles('**/requirements.txt') }}-${{
+            hashFiles('**/.pre-commit-config.yaml') }}
           # Note that the .terraform directory IS NOT included in the
           # cache because if we were caching, then we would need to use
           # the `-upgrade=true` option. This option blindly pulls down the