text/template: key/value assignment is reversed within range loop [1.20 backport]

[gopherbot]

@ianlancetaylor requested issue #60801 to be considered for backport to the next 1.20 minor release.

@gopherbot Please open backport to 1.20.

This is a regression since previous versions.

[gopherbot]

Change https://go.dev/cl/503576 mentions this issue: [release-branch.go1.20] text/template: set variables correctly in range assignment

[gopherbot]

Closed by merging 0306310 to release-branch.go1.20.