Use jq's IN() instead of index()

The end result is the same, but the construction is more ergonomic.

Dockerfile.template

@@ -63,7 +63,7 @@ RUN set -eux; \
 {{ if is_alpine then ( -}}
 	apk add --no-cache --virtual .ruby-builddeps \
 		autoconf \
-{{ if [ "3.1", "3.2" ] | index(env.version | rtrimstr("-rc")) then ( -}}
+{{ if env.version | rtrimstr("-rc") | IN("3.1", "3.2") then ( -}}
 {{ # https://github.com/docker-library/ruby/pull/438 -}}
 		bison \
 {{ ) else "" end -}}
@@ -87,7 +87,7 @@ RUN set -eux; \
 		openssl-dev \
 		patch \
 		procps \
-{{ if [ "3.1", "3.2" ] | index(env.version | rtrimstr("-rc")) then ( -}}
+{{ if env.version | rtrimstr("-rc") | IN("3.1", "3.2") then ( -}}
 		readline-dev \
 {{ ) else "" end -}}
 		ruby \
@@ -100,7 +100,7 @@ RUN set -eux; \
 	savedAptMark="$(apt-mark showmanual)"; \
 	apt-get update; \
 	apt-get install -y --no-install-recommends \
-{{ if [ "3.1", "3.2" ] | index(env.version | rtrimstr("-rc")) then ( -}}
+{{ if env.version | rtrimstr("-rc") | IN("3.1", "3.2") then ( -}}
 {{ # https://github.com/docker-library/ruby/pull/438 -}}
 		bison \
 {{ ) else "" end -}}
@@ -115,7 +115,7 @@ RUN set -eux; \
 		libgdbm-compat-dev \
 		libglib2.0-dev \
 		libncurses-dev \
-{{ if [ "3.1", "3.2" ] | index(env.version | rtrimstr("-rc")) then ( -}}
+{{ if env.version | rtrimstr("-rc") | IN("3.1", "3.2") then ( -}}
 		libreadline-dev \
 {{ ) else "" end -}}
 		libxml2-dev \

versions.sh

@@ -100,13 +100,13 @@ for version in "${versions[@]}"; do
 		*)
 			# YJIT
 			doc="$(jq <<<"$doc" -sc '
-				.[1][].arches? |= if . then with_entries(select(.key as $arch | [
+				.[1][].arches? |= if . then with_entries(select(.key | IN(
 					# https://github.com/ruby/ruby/blob/v3_2_0/doc/yjit/yjit.md ("currently supported for macOS and Linux on x86-64 and arm64/aarch64 CPUs")
 					# https://github.com/ruby/ruby/blob/v3_2_0/configure.ac#L3757-L3761
 					"amd64",
 					"arm64v8",
 					empty # trailing comma
-				] | index($arch))) else empty end
+				))) else empty end
 				| add
 			' - rust.json)"
 			;;