Just figured this out, hope it's helpful!
When I say "F with E on top" the fingering is

0
1
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3
3
x

Capo 4
Intro: C C/B Am7 F

C
Can't believe you're
C/B
Packing your bags
Am7                 F
Trying so hard not to cry

C
Had the best time 
C/B
And now it's the worst time
Am7                F
But we have to say goodbye

G
Don't promise that you're gonna write
Dm
Don't promise that you'll call
G                                                         F
Just promise that you won't forget we had it all

C
Cause you were mine 
Dm
For the summer
F
Now we know it's
F with E on top
Nearly over

C
Feels like snow
Dm
In september
F
But I always
F with E on top
Will remember

                C  Dm F C
You were my summer love
                            C  Dm F C
You always will be my summer love

(Verse)
(Chorus)

C  Dm F C
You were my summer love
                            C  Dm F F
You always will be my summer love

              G
So please don't make this any harder
F
We can't take this any farther
C                                                      F
And I know there's nothing that I wanna change to change

(chorus)