Bump alpine from 3.14.6 to 3.15.4 in /build (#1237)

Bumps alpine from 3.14.6 to 3.15.4.

---
updated-dependencies:
- dependency-name: alpine
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Cesar Rodriguez <cesar@accurics.com>

build/Dockerfile

@@ -21,7 +21,7 @@ RUN apk update && apk add git && \
 
 
 # -------- prod stage -------- #
-FROM alpine:3.14.6
+FROM alpine:3.15.4
 
 # create non root user
 RUN addgroup --gid 101 terrascan && \