Fix incorrect use of Swatinem/rust-cache

[cecton]

Description

I just discovered the other day that the Swatinem/cache action doesn't work
properly when using matrix. Apparently the cache key is the same for all the
different paths of the workflow matrix which makes Rust not re-use the correct
cache.

This should speed up our workflows a bit.

Related to yewstack/yew-autoprops#10 (comment)

Checklist

• I have reviewed my own code
• I have added tests

[github-actions]

Size Comparison

examples	master (KB)	pull request (KB)	diff (KB)	diff (%)
async_clock	100.243	100.243	0	0.000%
boids	173.724	173.724	0	0.000%
communication_child_to_parent	92.743	92.743	0	0.000%
communication_grandchild_with_grandparent	105.763	105.763	0	0.000%
communication_grandparent_to_grandchild	101.013	101.013	0	0.000%
communication_parent_to_child	89.082	89.082	0	0.000%
contexts	106.000	106.000	0	0.000%
counter	86.122	86.122	0	0.000%
counter_functional	86.509	86.509	0	0.000%
dyn_create_destroy_apps	88.931	88.931	0	0.000%
file_upload	100.041	100.041	0	0.000%
function_memory_game	172.342	172.342	0	0.000%
function_router	349.650	349.650	0	0.000%
function_todomvc	161.183	161.183	0	0.000%
futures	229.162	229.162	0	0.000%
game_of_life	110.120	110.120	0	0.000%
immutable	185.462	185.462	0	0.000%
inner_html	79.895	79.895	0	0.000%
js_callback	109.512	109.512	0	0.000%
keyed_list	199.568	199.568	0	0.000%
mount_point	82.788	82.788	0	0.000%
nested_list	113.881	113.881	0	0.000%
node_refs	90.319	90.319	0	0.000%
password_strength	1749.720	1749.720	0	0.000%
portals	93.461	93.461	0	0.000%
router	318.531	318.531	0	0.000%
simple_ssr	140.320	140.320	0	0.000%
ssr_router	386.976	386.976	0	0.000%
suspense	115.718	115.718	0	0.000%
timer	88.553	88.553	0	0.000%
timer_functional	97.912	97.912	0	0.000%
todomvc	141.337	141.337	0	0.000%
two_apps	85.824	85.824	0	0.000%
web_worker_fib	134.760	134.760	0	0.000%
web_worker_prime	184.966	184.966	0	0.000%
webgl	82.452	82.452	0	0.000%

✅ None of the examples has changed their size significantly.

[cecton]

Ok I think it's all working perfectly EXCEPT for the size comparison one but I don't want to dig so we can merge for now