ideally order of new additions should be deterministic

I guess somewhere some set or unordered dict in place.

In datalad we got two PRs (since we didn't react to initial in time) for the "same" change:
https://github.com/datalad/datalad/pull/5618 and https://github.com/datalad/datalad/pull/5622

I thought diffs would be identical and then the fix needs to be solely at the level of workflow but apparently there are differences in order:

```diff
1: 4e1365a77 ! 1: 59a016f50 Automated deployment to update contributors 2021-04-29
@@ Metadata
Author: github-actions

## Commit message ##
- Automated deployment to update contributors 2021-04-29
+ Automated deployment to update contributors 2021-04-30

## .all-contributorsrc ##
@@
@@ .all-contributorsrc
+ ]
+ },
+ {
-+ "login": "mattcieslak",
-+ "name": "Matt Cieslak",
++ "login": "mikapfl",
++ "name": "Mika Pflüger",
+ "contributions": [
+ "code"
+ ],
-+ "profile": "https://github.com/mattcieslak",
++ "profile": "https://github.com/mikapfl",
+ "avatar_url": [
-+ "https://avatars.githubusercontent.com/u/170026?v=4"
++ "https://avatars.githubusercontent.com/u/7226087?v=4"
+ ]
+ },
+ {
-+ "login": "mikapfl",
-+ "name": "Mika Pflüger",
++ "login": "mattcieslak",
++ "name": "Matt Cieslak",
+ "contributions": [
+ "code"
+ ],
-+ "profile": "https://github.com/mikapfl",
++ "profile": "https://github.com/mattcieslak",
+ "avatar_url": [
-+ "https://avatars.githubusercontent.com/u/7226087?v=4"
++ "https://avatars.githubusercontent.com/u/170026?v=4"
+ ]
}
],
@@ README.md: Sciences, Imaging Platform. This work is further facilitated by the
+
<sub>yetanothertestuser</sub>
💻
+
<sub>bhanuprasad14</sub>
💻
+
<sub>Christian Mönch</sub>
💻
-+
<sub>Matt Cieslak</sub>
💻
+
<sub>Mika Pflüger</sub>
💻
++
<sub>Matt Cieslak</sub>
💻
+
+
+

```