First of all, those're not errors, only warnings.
More specifically they tell you, that you have bad indentantion; meaning, that your "spaces" before lines are "incorrect"
When I select your code (which you send) and paste it in my editor, I can see that:
line 35 has tabulator indent (you pressed tab, or your editor put it there)
line 36 has spaces (you pressed space to indent the line)
line 37 has tabulator once again.
The same goes for lines 49;50;51
Line 53 is indented through spaces (the else statement, the if before has tabulators).
I'll try to paste the code here (from my editor) so you can see the errors in indentation:
nextRoundGravity = true;
PrintToChatAll("[Sourcemod] The next round gravity will be raised. Don't forget to buy the spacesuit.");
You can clearly see, that the nextRoundGravity is not indented same as the rest.
I hope this helps you. Have a good day